Reduced-cost Relativistic Equation-of-Motion Coupled Cluster Method based on Frozen Natural Spinors: A State-Specific Approach
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arXiv
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| Autori principali: | , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| author | Mukhopadhyay, Tamoghna Thapa, Mrinal Chamoli, Somesh Wang, Xubo Zhang, Chaoqun Nayak, Malaya K. Dutta, Achintya Kumar |
| author_facet | Mukhopadhyay, Tamoghna Thapa, Mrinal Chamoli, Somesh Wang, Xubo Zhang, Chaoqun Nayak, Malaya K. Dutta, Achintya Kumar |
| contents | We present the theoretical framework, implementation, and benchmark results for a reduced-cost relativistic equation-of-motion coupled cluster singles and doubles (EOM-CCSD) method based on state-specific frozen natural spinors (SS-FNS). In this approach, the state-specific frozen natural spinors are derived from the second-order algebraic diagrammatic construction (ADC(2)) method, providing a compact virtual space for excited-state calculations. The excitation energies computed with the SS-FNS-EE-EOM-CCSD method exhibit smooth convergence with respect to the truncation threshold and demonstrate significant improvements over those obtained using the conventional MP2-based FNS approach. We have implemented the relativistic SS-FNS-EE-EOM-CCSD method using both the four-component Dirac-Coulomb and the exact two-component atomic mean-field (X2CAMF) Hamiltonians to compute excitation energies and transition properties. The X2CAMF-based relativistic EOM-CCSD method emerges as a promising approach for large-scale excited-state calculations, achieving excellent agreement with the standard relativistic EOM-CCSD method based on the untruncated canonical spinor basis, but at a significantly reduced computational cost. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_07080 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Reduced-cost Relativistic Equation-of-Motion Coupled Cluster Method based on Frozen Natural Spinors: A State-Specific Approach Mukhopadhyay, Tamoghna Thapa, Mrinal Chamoli, Somesh Wang, Xubo Zhang, Chaoqun Nayak, Malaya K. Dutta, Achintya Kumar Chemical Physics We present the theoretical framework, implementation, and benchmark results for a reduced-cost relativistic equation-of-motion coupled cluster singles and doubles (EOM-CCSD) method based on state-specific frozen natural spinors (SS-FNS). In this approach, the state-specific frozen natural spinors are derived from the second-order algebraic diagrammatic construction (ADC(2)) method, providing a compact virtual space for excited-state calculations. The excitation energies computed with the SS-FNS-EE-EOM-CCSD method exhibit smooth convergence with respect to the truncation threshold and demonstrate significant improvements over those obtained using the conventional MP2-based FNS approach. We have implemented the relativistic SS-FNS-EE-EOM-CCSD method using both the four-component Dirac-Coulomb and the exact two-component atomic mean-field (X2CAMF) Hamiltonians to compute excitation energies and transition properties. The X2CAMF-based relativistic EOM-CCSD method emerges as a promising approach for large-scale excited-state calculations, achieving excellent agreement with the standard relativistic EOM-CCSD method based on the untruncated canonical spinor basis, but at a significantly reduced computational cost. |
| title | Reduced-cost Relativistic Equation-of-Motion Coupled Cluster Method based on Frozen Natural Spinors: A State-Specific Approach |
| topic | Chemical Physics |
| url | https://arxiv.org/abs/2505.07080 |