AI Article Synopsis
- The study revisits the theoretical basis for solving CCSD amplitude equations with a focus on identifying error sources and optimizing calculations using local orbital spaces.
- Four main error sources are analyzed, revealing that local orbital spaces can be effectively derived from lower-level MP2 calculations.
- An algorithm has been developed to accurately determine the necessary orbital spaces for single fragment energy calculations, showcasing its reliability and precision through numerical demonstrations.
Article Abstract
The theoretical foundation for solving coupled cluster singles and doubles (CCSD) amplitude equations to a desired precision in terms of independent fragment calculations using restricted local orbital spaces is reinvestigated with focus on the individual error sources. Four different error sources are identified theoretically and numerically and it is demonstrated that, for practical purposes, local orbital spaces for CCSD calculations can be identified from calculations at the MP2 level. The development establishes a solid theoretical foundation for local CCSD calculations for the independent fragments, and thus for divide-expand-consolidate coupled cluster calculations for large molecular systems with rigorous error control. Based on this theoretical foundation, we have developed an algorithm for determining the orbital spaces needed for obtaining the single fragment energies to a requested precision and numerically demonstrated the robustness and precision of this algorithm.
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| http://dx.doi.org/10.1063/1.4947019 | DOI Listing |
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