Real-Time Coupled Cluster Theory with Approximate Triples
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arXiv
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| Autori principali: | , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| _version_ | 1866913659660271616 |
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| author | Wang, Zhe Kristiansen, Håkon Emil Pedersen, Thomas Bondo Crawford, T. Daniel |
| author_facet | Wang, Zhe Kristiansen, Håkon Emil Pedersen, Thomas Bondo Crawford, T. Daniel |
| contents | In order to explore the effects of high levels of electron correlation on the real-time coupled cluster formalism and algorithmic behavior, we introduce a time-dependent implementation of the CC3 singles, doubles and approximate triples method. We demonstrate the validity of our derivation and implementation using specific applications of frequency-dependent properties. Terms with triples are calculated and added to the existing CCSD equations, giving the method a nominal $\textit{O}(N^{7})$ scaling. We also use a graphics processing unit (GPU) accelerated implementation to reduce the computational cost, which we find can speed up the calculation by up to a factor of 17 for test cases of water clusters. In addition, we compare the impact of using single-precision arithmetic compared to conventional double-precision arithmetic. We find no significant difference in polarizabilities and optical-rotation tensor results, but a somewhat larger error for first hyperpolarizabilities. Compared to linear response (LR) CC3 results, the percentage errors of RT-CC3 polarizabilities and RT-CC3 first hyperpolarizabilities are under 0.1% and 1%, respectively, for a water-molecule test case in a double-zeta basis set. Furthermore, we compare the dynamic polarizabilities obtained using RT-CC3, RT-CCSD, and time-dependent nonorthogonal orbital-optimized coupled cluster doubles (TDNOCCD), in order to examine the performance of RT-CC3 and the orbital-optimization effect using a set of ten-electron systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2407_18947 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Real-Time Coupled Cluster Theory with Approximate Triples Wang, Zhe Kristiansen, Håkon Emil Pedersen, Thomas Bondo Crawford, T. Daniel Chemical Physics Quantum Physics In order to explore the effects of high levels of electron correlation on the real-time coupled cluster formalism and algorithmic behavior, we introduce a time-dependent implementation of the CC3 singles, doubles and approximate triples method. We demonstrate the validity of our derivation and implementation using specific applications of frequency-dependent properties. Terms with triples are calculated and added to the existing CCSD equations, giving the method a nominal $\textit{O}(N^{7})$ scaling. We also use a graphics processing unit (GPU) accelerated implementation to reduce the computational cost, which we find can speed up the calculation by up to a factor of 17 for test cases of water clusters. In addition, we compare the impact of using single-precision arithmetic compared to conventional double-precision arithmetic. We find no significant difference in polarizabilities and optical-rotation tensor results, but a somewhat larger error for first hyperpolarizabilities. Compared to linear response (LR) CC3 results, the percentage errors of RT-CC3 polarizabilities and RT-CC3 first hyperpolarizabilities are under 0.1% and 1%, respectively, for a water-molecule test case in a double-zeta basis set. Furthermore, we compare the dynamic polarizabilities obtained using RT-CC3, RT-CCSD, and time-dependent nonorthogonal orbital-optimized coupled cluster doubles (TDNOCCD), in order to examine the performance of RT-CC3 and the orbital-optimization effect using a set of ten-electron systems. |
| title | Real-Time Coupled Cluster Theory with Approximate Triples |
| topic | Chemical Physics Quantum Physics |
| url | https://arxiv.org/abs/2407.18947 |