Quantum Processor DFT Simulation via Local Density Approximation

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Solution Overview

Problem

Conventional Density Functional Theory (DFT) simulations face a computational complexity bottleneck, particularly in simulating large chemical systems, leading to time-consuming calculations even on the most powerful supercomputers, which limits the efficiency of chemical compound simulations in pharmaceutical and material sciences.

Innovation Solution

Implementing density functional theory on quantum processors through local density approximation by iteratively updating an initial density matrix using quantum circuits, including operations on qubits to compute matrices and achieve convergence criteria, thereby reducing computational complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional DFT methods are used to simulate large chemical systems, then simulation accuracy is maintained, but computational time increases dramatically due to cubic scaling

Engineering Contradiction:
Improvesimulation accuracyVSAvoidcomputational time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the classical mechanical computational system with a quantum computational system. Quantum processors utilize quantum parallelism and superposition to perform DFT calculations, fundamentally changing the computational paradigm from classical sequential processing to quantum parallel processing, thereby achieving exponential speedup for large chemical systems

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the scaling parameter from cubic O(N³) to linear O(N) by implementing DFT on quantum processors. This parameter change is achieved through quantum algorithms that exploit the structure of the DFT equations, allowing the computational complexity to scale linearly with system size rather than cubically

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If system size is increased to simulate larger chemical compounds, then screening capability is improved, but computational complexity increases due to cubic scaling

Engineering Contradiction:
Improvescreening capabilityVSAvoidcomputational complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent substitutes quantum computational mechanics for classical computational mechanics, enabling the simulation of large chemical systems with thousands of atoms. The quantum processor's ability to naturally represent quantum states allows direct simulation of electronic structure without the cubic scaling bottleneck of classical methods

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent segments the computational task into quantum-processing components that can be executed in parallel. By dividing the DFT calculation into discrete quantum operations on the quantum processor, the system can handle larger chemical compounds while maintaining manageable computational complexity through parallel quantum processing

Inventive Principle:
Principle #1Segmentation

3Ease of manufacture

If classical supercomputers are used for DFT calculations, then existing infrastructure is utilized, but simulation speed is limited by cubic scaling wall

Engineering Contradiction:
Improveinfrastructure utilizationVSAvoidsimulation speed
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent replaces the classical supercomputer mechanical system with a quantum processor system. This substitution transitions from classical bits and sequential logic to quantum bits and quantum parallelism, fundamentally increasing simulation speed while overcoming the cubic scaling wall that limits classical supercomputers

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces dynamic quantum processing capabilities that adapt to the size and complexity of the chemical system being simulated. The quantum processor can dynamically adjust its computational resources and algorithms based on the problem requirements, enabling scalable performance that classical fixed-architecture supercomputers cannot achieve

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4575928A1Implementing density functional theory on quantum processors through local density approximation for simulating chemical compounds
Publication Date: 2025.06.25 TATA CONSULTANCY SERVICES LTD
  • EP4575928A1 patent drawingFigure 1
  • EP4575928A1 patent drawingFigure 2
  • EP4575928A1 patent drawingFigure 3A

AI summary

The disclosure relates generally to methods and systems for implementing density functional theory on quantum processors through local density approximation for simulating chemical compounds. Conventional methods implement the DFT simulations on classical processors which is time consuming. According to the present disclosure, initially a plurality of atomic coordinates of each atom of a given chemical compound whose one or more properties to be extracted, are obtained. Electron integrals, a core Hamiltonian, and a collocation matrix are computed from the plurality of atomic coordinates. The core Hamiltonian is diagonalized to obtain an initial density matrix of the chemical compound. The initial density matrix is further updated iteratively until a convergence criteria is satisfied using a local density approximation (LDA) to obtain a final density matrix. The final density matrix is used to extract the one or more properties of the chemical compound.