Ground energy calculation program, ground energy calculation device, and ground energy calculation method

Abstract

To solve the problem that nose may impact on a variational quantum eigensolver (VQE) for a noisy intermediate-scale quantum computer (NISQ) to deteriorate the expected value calculation accuracy thereof; and further that an increase in size of a handled molecule may increase the impact of the noise and further deteriorate the accuracy to impact on ground energy calculation accuracy of the molecule.SOLUTION: A ground energy calculation program causes a computer to execute processing including: dividing a target molecule into a plurality of fragments; calculating an energy value of each of a plurality of bath orbitals that corresponds to the fragment, for each divided fragment; selecting a predetermined number of first energy values from a plurality of the energy values, based on the calculated energy value; adding a first bath orbital that corresponds to the first energy value, of the plurality of bath orbitals, to the fragment; calculating energy of the fragment that includes the first bath orbital; and adding the energy calculated for each fragment so as to calculate ground energy of the target molecule.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a basis energy calculation technique. [Background technology]

[0002] By calculating the energy of a target molecule, the characteristics of the molecule can be understood. For example, the stable state of the molecular structure can be understood from the ground state energy of the target molecule, and the unstable state of the molecular structure can be understood from the excited energy. Understanding such molecular characteristics is useful for drug discovery and the discovery of new materials, so quantum chemical calculations are very important.

[0003] Currently, the development of quantum computers for quantum chemical calculations is progressing with the goal of FTQC (Fault Tolerant Quantum Computer), which is a quantum computer with quantum error tolerance. On the other hand, it is beginning to be said that even NISQ (Noisy Intermediate-Scale Quantum Computer), which has insufficient quantum error correction, can realize the superiority of quantum computers in fields such as quantum chemical calculations, quantum approximation optimization, and quantum machine learning.

[0004] NISQ is a medium-scale quantum computer with noise. Since NISQ has a limit on the time it can maintain a quantum state, it can only run shallow quantum circuits, i.e., small-scale quantum circuits with tens to hundreds of quantum bits.

[0005] In addition, current NISQ is easily affected by noise, and the execution results tend to fluctuate due to noise. The magnitude of the noise effect depends on the size of the quantum circuit (the number of quantum bits and gates), and the number of gates tends to increase as the number of quantum bits increases.

[0006] In addition, there is a variational algorithm for NISQ called VQE (Variational Quantum Eigensolver). In quantum chemical calculations, VQE is an algorithm that can search for ground states using quantum states and calculate ground state energies. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2019-537129 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the accuracy of VQE in calculating the expected value deteriorates due to the influence of noise. Furthermore, as the molecule to be handled becomes larger, a larger quantum circuit is required, so the influence of noise may become greater, and the degree of deterioration in the accuracy of VQE also becomes greater. The deterioration in the accuracy of VQE also affects the accuracy of calculating the ground state energy of a molecule using VQE in NISQ.

[0009] In one aspect, an object is to accurately calculate the ground state energy of a molecule. [Means for solving the problem]

[0010] In one embodiment, the ground energy calculation program causes a computer to execute a process of dividing a target molecule into a plurality of fragments, calculating an energy value of each of a plurality of bath orbitals corresponding to the fragment for each of the divided fragments, selecting a predetermined number of first energy values ​​from the plurality of energy values ​​based on the calculated energy values, adding a first bath orbital corresponding to the first energy value among the plurality of bath orbitals to the fragment, calculating the energy of the fragment including the first bath orbital, and adding up the energies calculated for each of the fragments, thereby calculating the ground energy of the target molecule. Effect of the Invention

[0011] In one aspect, the ground state energy of a molecule can be calculated with high accuracy. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram for explaining VQE. [Diagram 2] FIG. 2 is a diagram showing an example of quantum chemical calculation using VQE. [Diagram 3] FIG. 3 is a diagram for explaining problems with performing VQE in a noisy environment. [Figure 4] FIG. 4 is a diagram for explaining DMET. [Diagram 5] FIG. 5 is a diagram showing an example of the correlation between the number of bath orbitals and the calculation accuracy of the expected value of VQE. [Figure 6] FIG. 6 is a diagram showing an example of the configuration of the basis energy calculation device 10 according to this embodiment. [Figure 7] FIG. 7 is a flowchart showing the flow of the base energy calculation process according to this embodiment. [Figure 8] FIG. 8 is a flowchart showing the flow of the bath orbit addition process according to this embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of the hardware configuration of the basis energy calculation device 10 according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, examples of the base energy calculation program, the base energy calculation device, and the base energy calculation method according to the present embodiment will be described in detail with reference to the drawings. Note that the present embodiment is not limited by these examples. Also, each example can be appropriately combined within a range that does not cause a contradiction.

[0014] First, the VQE used in this embodiment will be described. Fig. 1 is a diagram for explaining VQE. VQE is, for example, a variational algorithm for NISQ, and as shown in Fig. 1, is executed by a method of alternately using NISQ (quantum computer) and a classical computer, which is a general computer currently in widespread use.

[0015] In this method using VQE, for example, as shown in FIG. 1, a quantum computer executes a quantum circuit with parameters, and a classical computer obtains the value of a quantum bit that is the execution result. Next, the classical computer calculates an expected value resulting from the execution of the quantum circuit based on, for example, the obtained value of the quantum bit, and optimizes the parameters from the expected value. Then, for example, as shown in FIG. 1, the optimized parameters are set in the quantum circuit, and the execution of the quantum circuit and the optimization of the parameters are repeated until the expected value converges. A more specific explanation will be given with reference to FIG. 2.

[0016] Fig. 2 is a diagram showing an example of quantum chemical calculation using VQE. Fig. 2 shows an example in which a quantum computer executes an ansatz, which is a quantum circuit with parameters, and a classical computer optimizes the parameters.

[0017] The quantum circuit shown in Fig. 2 includes, for example, an initialization gate for initializing the quantum state of each quantum bit, a gate group U(θ) for constructing a trial state (the parameter θ is actually → above θ), and H obtained by gate-transforming the Hamiltonian to be calculated. As shown in Fig. 2, the quantum computer initializes, for example, the quantum state of each quantum bit, inserts it into a gate with a parameter, and measures the value of each quantum bit, i.e., the quantum state, as the execution result.

[0018] Next, the classical computer calculates an expectation value from the measured value of each quantum bit, and optimizes parameters based on the expectation value using an existing optimization method such as gradient descent, for example, as shown in Figure 2. Then, for example, the optimized parameters are set in the quantum circuit, and the execution of the quantum circuit and the optimization of the parameters are repeated until the expectation value converges.

[0019] However, the execution of a quantum circuit using VQE has a problem that, for example, the accuracy of the expected value calculation deteriorates due to the influence of noise. FIG. 3 is a diagram for explaining the problem of the execution of VQE in a noise-containing environment. As shown in FIG. 3, for example, the influence of noise makes it difficult to calculate an accurate expected value, and furthermore, to optimize parameters. As a result, the expected value does not converge, and the accuracy of the execution of the quantum circuit using VQE deteriorates. In addition, when the molecule to be handled becomes larger, a larger quantum circuit is required, so that the influence of noise may become larger accordingly, and the degree of deterioration in the accuracy of the execution of the quantum circuit using VQE also becomes larger. Such deterioration in the accuracy of the execution of the quantum circuit using VQE also affects the accuracy when the ground energy of the molecule is calculated using VQE in NISQ.

[0020] Therefore, in this embodiment, one of the objectives is, for example, to reduce the number of quantum bits in the quantum circuit used in VQE, reduce the effect of noise on VQE, and accurately calculate the ground state energy of the molecule.

[0021] For this purpose, in this embodiment, the molecule to be treated is divided into multiple fragments using the existing technology DMET (Density Matrix Embedding Theory). DMET is an existing method for dividing a molecule into multiple fragments and adding up the energies of each fragment to obtain the energy of the entire molecule. By dividing a molecule into multiple fragments, the number of orbitals of each fragment can be reduced compared to the entire molecule, and the number of quantum bits can be reduced.

[0022] FIG. 4 is a diagram for explaining DMET. As shown in FIG. 4, in DMET, for example, a molecule is divided into a plurality of fragments. In the example of FIG. 4, four molecules are divided into two fragments, fragment 1 and fragment 2, each of which has two molecules. Each fragment includes, for example, an orbital that each fragment has and a bath orbital that is a part of the orbital of the other fragment. The orbital that the fragment has is, for example, an orbital into which an electron can enter. In addition, the bath orbital expresses, for example, an interaction between fragments. As shown in FIG. 4, for example, fragment 1 has an orbital that fragment 1 has and a bath orbital that is a part of the orbital of fragment 2. Then, the energy of the entire molecule can be calculated by calculating the energy for each fragment and adding them up.

[0023] Also, for example, in DMET, the number of quantum bits required for the calculation of a fragment is determined by the number of orbitals of the fragment + the number of bath orbitals. Also, in DMET, for example, by dividing a molecule, the number of orbitals of each fragment can be reduced compared to the whole molecule, so the number of quantum bits of the quantum circuit used in VQE can be reduced, and the influence of noise on VQE can be reduced. However, since the number of quantum bits required is equal to the number of bath orbitals, in this embodiment, the number of bath orbitals included in the fragment is further adjusted. Details of the adjustment of the number of bath orbitals will be described later, but for example, only the top N (N is any natural number) bath orbitals that have a large influence on the interaction between fragments are included in the fragment. This allows the number of quantum bits of the fragment to be reduced, and the influence of noise on VQE, particularly on the calculation of the expected value of VQE, can be reduced.

[0024] FIG. 5 is a diagram showing an example of the correlation between the number of bath orbitals and the calculation accuracy of the expected value of VQE. As shown in FIG. 5, for example, the more the number of bath orbitals, the more accurately the interaction between fragments can be expressed. However, as the number of bath orbitals increases, the number of quantum bits increases, so the effect of noise increases accordingly, and the error from the optimal expected value also increases, resulting in a deterioration in accuracy. Conversely, for example, as the number of bath orbitals decreases, the effect of noise decreases, but if the number of bath orbitals decreases too much, the interaction between fragments cannot be expressed, the error from the optimal expected value increases, resulting in a deterioration in accuracy. Therefore, as shown in FIG. 5, by adjusting the number of bath orbitals to a number that is small enough to express the interaction between fragments, the error from the optimal expected value decreases, and the accuracy can be improved.

[0025] Therefore, in this embodiment, the molecule to be treated is divided into multiple fragments using DMET, and the number of bath orbitals contained in each fragment is adjusted, thereby reducing the influence of noise on the calculation of the VQE expectation value, and ultimately calculating the ground state energy of the molecule with high accuracy.

[0026] (Functional configuration of the base energy calculation device 10) Next, the functional configuration of the basis energy calculation device 10 which is the main operating subject of this embodiment will be described. FIG. 6 is a diagram showing an example of the configuration of the basis energy calculation device 10 according to this embodiment. The basis energy calculation device 10 shown in FIG. 6 is, for example, a quantum computer such as NISQ, a server computer, or an information processing device such as a desktop PC (Personal Computer) or a notebook PC. Note that, although FIG. 6 shows the basis energy calculation device 10 as one computer, it may be a distributed computing system composed of a plurality of computers. Also, for example, the basis energy calculation device 10 may be a cloud computer device, part of which or the whole of which is managed by a service provider that provides a cloud computing service.

[0027] As shown in FIG. 6, the basis energy calculation device 10 includes, for example, a communication unit 20, a storage unit 30, and a control unit 40.

[0028] The communication unit 20 is a processing unit that controls communication with other devices, and is, for example, a communication interface such as a network interface card or a Universal Serial Bus (USB) interface.

[0029] The storage unit 30 has a function of storing various data and programs executed by the control unit 40, and is realized by a storage device such as a memory or a hard disk. The storage unit 30 stores quantum circuit information 31, quantum state information 32, fragment information 33, and the like.

[0030] The quantum circuit information 31 stores, for example, information about a quantum circuit executed by the basis energy calculation device 10. More specifically, the quantum circuit information 31 stores, for example, information about a quantum circuit with parameters as shown in FIG.

[0031] The quantum state information 32 stores, for example, information on a quantum state that is a state of a quantum bit input when the basis energy calculation device 10 executes a quantum circuit. In addition, the quantum state information 32 may store, for example, information on a quantum state that is a state of a quantum bit output from a quantum circuit executed by the basis energy calculation device 10.

[0032] For example, information on fragments divided using DMET is stored in the fragment information 33. More specifically, for example, the orbital and bath orbital of each fragment, the number of each orbital, the energy and the number of electrons calculated for each fragment, etc. may be stored in the fragment information 33.

[0033] The above information stored in the storage unit 30 is merely an example, and the storage unit 30 can store various information other than the above information.

[0034] The control unit 40 is a processing unit that controls the entire basis energy calculation device 10, and is, for example, a processor. The control unit 40 includes a division unit 41, a calculation unit 42, an addition unit 43, and an output unit 44. Each processing unit is an example of an electronic circuit included in the processor or an example of a process executed by the processor.

[0035] The division unit 41 divides the target molecule into a plurality of fragments using, for example, DMET.

[0036] The calculation unit 42 calculates, for example, energy values ​​of each of a plurality of bath orbitals corresponding to the fragments for each fragment divided by the division unit 41. In calculating the bath orbitals, for example, the calculation unit 42 calculates a one-electron reduced density matrix (1-RDM) of the entire target molecule. Note that the density matrix is, for example, a matrix representing a quantum state. Then, the calculation unit 42 generates a matrix excluding the orbitals included in the fragments from the calculated 1-RDM, diagonalizes the generated matrix, and calculates eigenvalues ​​of the matrix as energy values ​​of the bath orbitals.

[0037] Furthermore, the calculation unit 42 calculates the energy of a fragment including the first bath orbital added by the addition unit 43, and calculates the ground state energy of the target molecule by adding up the energies calculated for each fragment.

[0038] The adding unit 43 selects a predetermined number of first energy values ​​from the plurality of energy values ​​based on, for example, the energy values ​​of the plurality of bath orbitals calculated by the calculating unit 42. Note that, regarding the selection of the predetermined number of first energy values, for example, the predetermined number of first energy values ​​may be selected in descending order of the energy values ​​of the plurality of bath orbitals.

[0039] Furthermore, the adding unit 43 adds, for example, a first bath orbital corresponding to a first energy value among the multiple bath orbitals to the fragment. That is, among the multiple bath orbitals, bath orbitals other than the first bath orbital are not added to the fragment, and the number of quantum bits can be reduced accordingly.

[0040] The output unit 44 outputs, for example, the ground state energy of the target molecule calculated by the calculation unit 42. The output of the ground state energy may be, for example, displayed via a display of the ground state energy calculation device 10, or may be transmitted to a classical computer communicably connected to the ground state energy calculation device 10.

[0041] (Processing flow) Next, the base energy calculation process executed by the base energy calculation device 10 will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the flow of the base energy calculation process according to this embodiment.

[0042] First, as shown in FIG. 7, the basis energy calculation device 10 calculates, for example, 1-RDM of the entire target molecule (step S101).

[0043] Next, the basis energy calculation device 10 divides the target molecule into a plurality of fragments using, for example, DMET (step S102). Note that the subsequent processes of steps S103 to S106 are executed for each of the fragments divided in step S102.

[0044] Next, the basis energy calculation apparatus 10 adds, for example, N bath orbitals to the fragment (step S103). An example of the bath orbital addition process in step S103 will be described more specifically with reference to FIG.

[0045] Fig. 8 is a flowchart showing the flow of the bath orbital addition process according to this embodiment. First, as shown in Fig. 8, the base energy calculation device 10 calculates the energy of the bath orbital from the 1-RDM of the entire target molecule calculated in step S101 (step S201). More specifically, for example, the base energy calculation device 10 generates a matrix from the calculated 1-RDM excluding the orbitals included in the fragment, diagonalizes the generated matrix, and calculates the eigenvalues ​​of the matrix as the energy values ​​of the bath orbital.

[0046] Next, the ground state energy calculation device 10 arranges the bath orbitals as candidates for the bath orbital according to the degree of influence on the interaction between the fragments calculated from the energy of the bath orbital calculated in step S201 (step S202). Note that the candidates for the bath orbital are, for example, candidates for the bath orbital to be added to the fragment.

[0047] Next, the basis energy calculation device 10 adds, for example, the top N bath orbitals from the candidates of the bath orbitals arranged in step S202 to the fragment as the formal bath orbitals to be adopted (step S203). That is, for example, by including only the top N bath orbitals that have a large effect on the interaction between the fragments in the fragment, the number of quantum bits of the fragment can be reduced, and the effect of noise on the calculation of the expected value of the VQE can be reduced. After executing step S203, the bath orbital addition process shown in FIG. 8 is completed, and the process returns to step S103 of the basis energy calculation process shown in FIG. 7.

[0048] Next, the basis energy calculation device 10 creates a Hamiltonian, for example, taking into account the penalty (step S104).

[0049] Next, the basis energy calculation device 10 calculates, for example, the energy of the fragment to which the bath orbital has been added in step S103 (step S105).

[0050] Next, the ground energy calculation device 10 calculates, for example, the number of electrons of the fragment to which the bath orbital is added in step S103 (step S106). The ground energy calculation device 10 executes the processes of steps S103 to S106 for each fragment divided in step S102, and after executing the processes for all the fragments divided in step S102, transitions to step S107.

[0051] Next, the basis energy calculation device 10 adds up the energies of the fragments calculated in step S105, for example (step S107).

[0052] Next, the ground energy calculation device 10 sums up the number of electrons of each fragment calculated in step S106 to obtain the total number of electrons of the fragment, and determines whether the total number of electrons matches the total number of electrons of the target molecule (step S108). If the two numbers of electrons do not match (step S108: No), the ground energy calculation device 10 updates, for example, the penalty value (step S109) and repeats the process from step S103.

[0053] On the other hand, if the two numbers of electrons match (step S108: Yes), the ground energy calculation device 10 outputs, for example, the energy summed in step S107 as the ground energy of the target molecule (step S110). After executing step S110, the ground energy calculation process shown in FIG. 7 ends.

[0054] (effect) As described above, the ground energy calculation device 10 divides a target molecule into a plurality of fragments, calculates an energy value of each of a plurality of bath orbitals corresponding to the fragment for each of the divided fragments, selects a predetermined number of first energy values ​​from the plurality of energy values ​​based on the calculated energy values, adds a first bath orbital corresponding to the first energy value among the plurality of bath orbitals to the fragment, calculates the energy of the fragment including the first bath orbital, and calculates the ground energy of the target molecule by adding up the energies calculated for each of the fragments.

[0055] In this way, the ground state energy calculation device 10 adds a predetermined number of bath orbitals to the fragments based on the energy of the bath orbitals calculated for each fragment obtained by dividing the target molecule, and sums up the energies of each fragment. This allows the ground state energy calculation device 10 to accurately calculate the ground state energy of the molecule.

[0056] Furthermore, the process of selecting the first energy values ​​executed by the basis energy calculation device 10 includes a process of selecting a predetermined number of first energy values ​​in descending order of the calculated energy values.

[0057] This allows the ground state energy calculation device 10 to accurately calculate the ground state energy of the molecule.

[0058] In addition, the basis energy calculation device 10 calculates 1-RDM of the entire target molecule, and the process of calculating the energy value of each of a plurality of bath orbitals executed by the basis energy calculation device 10 includes a process of generating a matrix from the calculated 1-RDM excluding orbitals contained in the fragment, diagonalizing the generated matrix, and calculating eigenvalues ​​of the matrix as energy values.

[0059] This allows the ground state energy calculation device 10 to accurately calculate the ground state energy of the molecule.

[0060] (system) The information including the processing procedures, control procedures, specific names, various data and parameters shown in the above documents and drawings may be changed arbitrarily unless otherwise specified. In addition, the specific examples, distributions, numerical values, etc. described in the embodiments are merely examples and may be changed arbitrarily.

[0061] In addition, the specific form of distribution or integration of the components of the base energy calculation device 10 is not limited to the illustrated one. For example, the calculation unit 42 of the base energy calculation device 10 may be distributed to a plurality of processing units, or the calculation unit 42 and the addition unit 43 of the base energy calculation device 10 may be integrated into one processing unit. In other words, all or a part of the components may be functionally or physically distributed or integrated in any unit according to various loads and usage conditions. Furthermore, all or any part of the processing functions of each device may be realized by a CPU (Central Processing Unit) and a program analyzed and executed by the CPU, or may be realized as hardware using wired logic.

[0062] Fig. 9 is a diagram showing an example of a hardware configuration of the basis energy calculation device 10 according to the present embodiment. As shown in Fig. 9, the basis energy calculation device 10 includes a communication interface 10a, a hard disk drive (HDD) 10b, a memory 10c, and a processor 10d. The components shown in Fig. 9 are connected to each other via a bus or the like.

[0063] The communication interface 10a is a network interface card or the like, and communicates with other information processing devices. The HDD 10b stores, for example, programs and data for operating each function of the base energy calculation device 10.

[0064] The processor 10d is a CPU, a micro processing unit (MPU), a graphics processing unit (GPU), etc. The processor 10d may be realized by an integrated circuit such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The processor 10d reads out a program that executes the same processes as the respective processing units shown in FIG. 6 from the HDD 10b, etc., and loads the program in the memory 10c. As a result, the processor 10d can operate as a hardware circuit that executes a process that realizes each function of the base energy calculation device 10.

[0065] In addition, the base energy calculation device 10 can realize the same functions as the above embodiment by reading the above program from a recording medium by a medium reading device and executing the read program. Note that the program in this other embodiment is not limited to being executed by the base energy calculation device 10. For example, the above embodiment may be similarly applied to a case where another information processing device executes the program, or a case where another information processing device and the base energy calculation device 10 cooperate to execute the program.

[0066] The program may be distributed via a network such as the Internet. The program may be recorded in a computer-readable storage medium such as a hard disk, a flexible disk (FD), a CD-ROM, a magneto-optical disk (MO), or a digital versatile disk (DVD). The program may be executed by being read from the storage medium by the basis energy calculation device 10 or the like.

[0067] The following supplementary notes are further disclosed regarding the embodiments including the above examples.

[0068] (Appendix 1) Divide the target molecule into multiple fragments, Calculating energy values ​​of each of a plurality of bath orbitals corresponding to each of the divided fragments; selecting a predetermined number of first energy values ​​from the plurality of energy values ​​based on the calculated energy values; adding a first bath orbital of the plurality of bath orbitals corresponding to the first energy value to the fragment; Calculating the energy of the fragment including the first bath orbital; Calculate the ground state energy of the target molecule by adding up the energies calculated for each of the fragments. A ground-base energy calculation program that causes a computer to execute a process.

[0069] (Supplementary Note 2) The process of selecting the first energy value includes: A predetermined number of the first energy values ​​are selected in order from the highest of the calculated energy values. 2. The ground state energy calculation program according to claim 1, further comprising the steps of:

[0070] (Appendix 3) Calculate the 1-RDM (one-electron reduced density matrix) of the entire target molecule causing the computer to execute a process; The process of calculating the energy value of each of the plurality of bath orbitals includes: A matrix is ​​generated from the calculated 1-RDM by excluding the orbitals included in the fragment; The generated matrix is ​​diagonalized, and the eigenvalues ​​of the matrix are calculated as the energy values. 3. The ground state energy calculation program according to claim 1 or 2, comprising the steps of:

[0071] (Appendix 4) Divide the target molecule into multiple fragments, Calculating energy values ​​of each of a plurality of bath orbitals corresponding to each of the divided fragments; selecting a predetermined number of first energy values ​​from the plurality of energy values ​​based on the calculated energy values; adding a first bath orbital of the plurality of bath orbitals corresponding to the first energy value to the fragment; Calculating the energy of the fragment including the first bath orbital; Calculate the ground state energy of the target molecule by adding up the energies calculated for each of the fragments. A basis energy calculation device comprising a control unit for executing processing.

[0072] (Supplementary Note 5) The process of selecting the first energy value includes: A predetermined number of the first energy values ​​are selected in order from the highest of the calculated energy values. 5. The basis energy calculation device according to claim 4, further comprising a process.

[0073] (Appendix 6) Calculate the 1-RDM (one-electron reduced density matrix) of the entire target molecule The control unit executes the process, The process of calculating the energy value of each of the plurality of bath orbitals includes: A matrix is ​​generated from the calculated 1-RDM by excluding the orbitals included in the fragment; The generated matrix is ​​diagonalized, and the eigenvalues ​​of the matrix are calculated as the energy values. 6. The basis energy calculation device according to claim 4 or 5, further comprising a process.

[0074] (Appendix 7) Divide the target molecule into multiple fragments, Calculating energy values ​​of each of a plurality of bath orbitals corresponding to each of the divided fragments; selecting a predetermined number of first energy values ​​from the plurality of energy values ​​based on the calculated energy values; adding a first bath orbital of the plurality of bath orbitals corresponding to the first energy value to the fragment; Calculating the energy of the fragment including the first bath orbital; Calculate the ground state energy of the target molecule by adding up the energies calculated for each of the fragments. A method for calculating basis energy, the processing of which is executed by a computer.

[0075] (Supplementary Note 8) The process of selecting the first energy value includes: A predetermined number of the first energy values ​​are selected in order from the highest of the calculated energy values. 8. The method for calculating ground energy according to claim 7, further comprising the steps of:

[0076] (Appendix 9) Calculate the 1-RDM (one-electron reduced density matrix) of the entire target molecule The process is executed by the computer, The process of calculating the energy value of each of the plurality of bath orbitals includes: A matrix is ​​generated from the calculated 1-RDM by excluding the orbitals included in the fragment; The generated matrix is ​​diagonalized, and the eigenvalues ​​of the matrix are calculated as the energy values. 9. The method for calculating ground energy according to claim 7 or 8, comprising the steps of:

[0077] (Appendix 10) A processor; a memory operatively connected to the processor; A basis energy calculation device comprising: Divide the target molecule into multiple fragments, Calculating energy values ​​of each of a plurality of bath orbitals corresponding to each of the divided fragments; selecting a predetermined number of first energy values ​​from the plurality of energy values ​​based on the calculated energy values; adding a first bath orbital of the plurality of bath orbitals corresponding to the first energy value to the fragment; Calculating the energy of the fragment including the first bath orbital; Calculate the ground state energy of the target molecule by adding up the energies calculated for each of the fragments. A basis energy calculation device that executes processing. [Explanation of symbols]

[0078] 10. Ground-Base Energy Calculation Device 10a Communication Interface 10b HDD 10c Memory 10d Processor 20 Communications Department 30 Storage section 31 Quantum circuit information 32 Quantum state information 33 Fragment Information 40 Control section 41 Split part 42 Calculation section 43 Addition 44 Output section

Claims

1. Divide the target molecule into multiple fragments, Calculating energy values ​​of each of a plurality of bath orbitals corresponding to each of the divided fragments; selecting a predetermined number of first energy values ​​from the plurality of energy values ​​based on the calculated energy values; adding a first bath orbital of the plurality of bath orbitals corresponding to the first energy value to the fragment; Calculating the energy of the fragment including the first bath orbital; Calculate the ground state energy of the target molecule by adding up the energies calculated for each of the fragments. A ground-base energy calculation program that causes a computer to execute a process.

2. The process of selecting the first energy value includes: A predetermined number of the first energy values ​​are selected in order from the highest of the calculated energy values.

2. The ground state energy calculation program according to claim 1, further comprising a process for calculating a ground state energy.

3. Calculate the 1-RDM (one-electron reduced density matrix) of the entire target molecule causing the computer to execute a process; The process of calculating the energy value of each of the plurality of bath orbitals includes: A matrix is ​​generated by excluding the orbitals included in the fragment from the calculated 1-RDM; The generated matrix is ​​diagonalized, and the eigenvalues ​​of the matrix are calculated as the energy values.

3. The ground state energy calculation program according to claim 1, further comprising a process for calculating the ground state energy.

4. Divide the target molecule into multiple fragments, Calculating energy values ​​of each of a plurality of bath orbitals corresponding to each of the divided fragments; selecting a predetermined number of first energy values ​​from the plurality of energy values ​​based on the calculated energy values; adding a first bath orbital of the plurality of bath orbitals corresponding to the first energy value to the fragment; Calculating the energy of the fragment including the first bath orbital; Calculate the ground state energy of the target molecule by adding up the energies calculated for each of the fragments. A basis energy calculation device comprising a control unit for executing processing.

5. Divide the target molecule into multiple fragments, Calculating energy values ​​of each of a plurality of bath orbitals corresponding to each of the divided fragments; selecting a predetermined number of first energy values ​​from the plurality of energy values ​​based on the calculated energy values; adding a first bath orbital of the plurality of bath orbitals corresponding to the first energy value to the fragment; Calculating the energy of the fragment including the first bath orbital; Calculate the ground state energy of the target molecule by adding up the energies calculated for each of the fragments. A method for calculating basis energy, the processing of which is executed by a computer.

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