Quantum Chemical Active Space Selection from Orbital Occupancy Data
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Solution Overview
Problem
The determination of active space in quantum chemical calculations is subjective and lacks a definite rule, affecting the accuracy and efficiency of calculations.
Innovation Solution
An information output program that applies principal component analysis to occupancy number data from molecular orbitals to automatically determine an active space, enhancing calculation accuracy and resource efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If active space is designated using HOMO-m/LUMO+n type scheme, then the amount of calculation is reduced, but the accuracy of quantum chemical calculations deteriorates due to subjectivity in determination
Solution Approach 1:
The system automatically designates the active space by itself using principal component analysis on occupancy number data, eliminating the need for user input and subjective judgment. The active space designation is performed autonomously based on objective mathematical analysis of the electronic structure data.
Solution Approach 2:
The manual, subjective process of active space designation by users is replaced with an automated computational method using principal component analysis. This substitutes human judgment with an objective mathematical algorithm that analyzes occupancy number variations to identify significant molecular orbitals.
2Measurement precision
If all molecular orbitals are used for variational calculation, then the accuracy of quantum chemical calculations is improved, but the amount of calculation increases significantly
Solution Approach 1:
The method extracts only the significant molecular orbitals that contribute to the active space based on principal component analysis of occupancy number data. By identifying and extracting the essential orbitals that capture the most important electronic structure information, the calculation is reduced to only those orbitals that truly matter for accuracy.
Solution Approach 2:
Instead of using all molecular orbitals (excessive action), the method uses a partial subset of orbitals that are identified as significant through principal component analysis. This partial action is sufficient to maintain calculation accuracy while reducing the computational burden.
3Ease of operation
If active space is designated by user subjectivity, then the determination process is simple, but the reliability of the active space designation deteriorates
Solution Approach 1:
The system performs active space designation autonomously without requiring user input or judgment. The reliability is improved by using objective principal component analysis on occupancy number data, while the ease of operation is maintained because the user simply needs to execute the calculation without making subjective decisions.
Solution Approach 2:
The method uses occupancy number data as feedback to objectively determine the active space. By analyzing how occupancy numbers change during the calculation process, the system identifies which molecular orbitals are most significant, providing a reliable and objective basis for active space designation that removes subjective bias.
Data Source
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AI summary
An information output program for causing a computer to execute a process includes acquiring occupancy number data that includes a time series of occupancy numbers for each of a plurality of molecular orbitals, executing principal component analysis on the occupancy number data, and outputting information on an active space that corresponds to a subset used for a quantum chemical calculation, among the plurality of molecular orbitals, based on a result of the principal component analysis.