Linear scaling perturbative triples correction approximations for open-shell domain-based local pair natural orbital coupled cluster singles and doubles theory [DLPNO-CCSD(T0/T)]
Autor: | Dimitrios G. Liakos, Frank Neese, Masaaki Saitow, Yang Guo, Christoph Riplinger, Ute Becker |
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Rok vydání: | 2020 |
Předmět: |
Physics
010304 chemical physics General Physics and Astronomy Basis function 010402 general chemistry Space (mathematics) 01 natural sciences 0104 chemical sciences Coupled cluster Fock matrix 0103 physical sciences Physics::Atomic and Molecular Clusters Linear scale Physical and Theoretical Chemistry Open shell Scaling Basis set Mathematical physics |
Zdroj: | The Journal of Chemical Physics. 152:024116 |
ISSN: | 1089-7690 0021-9606 |
Popis: | The coupled cluster method with single-, double-, and perturbative triple excitations [CCSD(T)] is considered to be one of the most reliable quantum chemistry theories. However, the steep scaling of CCSD(T) has limited its application to small or medium-sized systems for a long time. In our previous work, the linear scaling domain based local pair natural orbital CCSD variant (DLPNO-CCSD) has been developed for closed-shell and open-shell. However, it is known from extensive benchmark studies that triple-excitation contributions are important to reach chemical accuracy. In the present work, two linear scaling (T) approximations for open-shell DLPNO-CCSD are implemented and compared: (a) an algorithm based on the semicanonical approximation, in which off-diagonal Fock matrix elements in the occupied space are neglected [referred to as DLPNO-(T0)]; and (b) an improved algorithm in which the triples amplitudes are computed iteratively [referred to as DLPNO-(T)]. This work is based on the previous open-shell DLPNO-CCSD algorithm [M. Saitow et al., J. Chem. Phys. 146, 164105 (2017)] as well as the iterative (T) correction for closed-shell systems [Y. Guo et al., J. Chem. Phys. 148, 011101 (2018)]. Our results show that the new open-shell perturbative corrections, DLPNO-(T0/T), can predict accurate absolute and relative correlation energies relative to the canonical reference calculations with the same basis set. The absolute energies from DLPNO-(T) are significantly more accurate than those of DLPNO-(T0). The additional computational effort of DLPNO-(T) relative to DLPNO-(T0) is a factor of 4 on average. We report calculations on systems with more than 4000 basis functions. |
Databáze: | OpenAIRE |
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