Quantum Chemical Structure Optimization With Dual Convergence Criteria
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Solution Overview
Problem
The computational complexity and time required for determining a stable structure of a substance using density functional theory (DFT) are high due to the need for iterative calculations until convergence conditions are satisfied, particularly when total energy transitions to minute fluctuations, leading to prolonged computation times.
Innovation Solution
A quantum chemical computation method that uses a logical OR of two convergence conditions: one related to the magnitude of the force acting on atoms and another related to the energy change rate, to terminate the iterative updating process when either condition is satisfied, thereby reducing computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If structure optimization is performed by iteratively performing DFT until force convergence is satisfied, then a stable structure of the substance is determined, but the computation time becomes prolonged when total energy transitions to minute fluctuations
Solution Approach 1:
The patent changes the convergence criterion from force-based to energy-based. Instead of requiring force convergence (|Fi| < |F|) for all atoms, the patent uses energy change rate convergence (|E(n) - E(n-1)| < E_th), which directly addresses the problem of prolonged computation time when total energy transitions to minute fluctuations. This parameter change allows the calculation to terminate earlier while still ensuring the system has reached a stable state.
2Reliability
If the number of repetitions of DFT calculation is increased to achieve force convergence, then the convergence condition is satisfied, but the computational complexity increases
Solution Approach 1:
The patent fundamentally changes the convergence parameter from force magnitude to energy change rate. The new convergence condition |E(n) - E(n-1)| < E_th provides a more direct measure of system stability and requires fewer iterative calculations to satisfy, thereby reducing computational complexity while maintaining reliability in determining the stable structure.
Data Source
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AI summary
The computational complexity for determining a stable structure of a substance is reduced. An information processing apparatus 10 initially sets the positions of a plurality of atoms constituting a substance in position information 2 indicating the positions of the plurality of atoms, and iteratively updates the positions of the plurality of atoms. When the positions of the plurality of atoms are initially set or updated, the information processing apparatus 10 calculates the total energy of the substance. When the positions of the plurality of atoms are initially set or updated, the information processing apparatus 10 calculates the magnitude of the force acting on each of the plurality of atoms. When the positions of the plurality of atoms are updated, the information processing apparatus 10 calculates an energy change rate indicating the degree of a change in the total energy of the substance before and after the updating. Then, when at least one of a first convergence condition 3 related to the magnitude of the force and a second convergence condition 4 related to the energy change rate is satisfied, the information processing apparatus 10 terminates the updating of the positions of the plurality of atoms and acquires the position information 2 at the termination.