A reduced-cost two-component relativistic equation-of-motion coupled cluster method for the double electron attachment problem
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arXiv
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| Format: | Preprint |
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2026
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| _version_ | 1866911553615298560 |
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| author | Mandal, Sujan Mukhopadhyay, Tamoghna Dutta, Achintya Kumar |
| author_facet | Mandal, Sujan Mukhopadhyay, Tamoghna Dutta, Achintya Kumar |
| contents | We present a computationally efficient relativistic formulation of the equation-of-motion coupled-cluster method for the double electron attachment problem. In this work, the exact two-component Hamiltonian within the atomic mean-field approximation is employed, yielding results that are in close agreement with the corresponding four-component calculations. However, canonical DEA-EOM-CCSD calculations become prohibitively expensive for heavy elements and large basis sets due to the substantial memory requirements associated with complex 3p1h excitation manifold. To address this limitation, we introduce a state-specific frozen natural spinor basis that significantly reduces the virtual space through two controllable truncation thresholds. Furthermore, the use of Cholesky decomposition for the two-electron integrals provides an additional reduction in computational cost and memory. The performance of the proposed approach is demonstrated through calculations of double ionization potentials and excitation energies for group-12 and group-14 heavy elements. Vertical excitation energies for heavy chalcogen dimers are also presented. In addition, a range of diatomic spectroscopic constants is evaluated for group-13 halides. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2603_28441 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | A reduced-cost two-component relativistic equation-of-motion coupled cluster method for the double electron attachment problem Mandal, Sujan Mukhopadhyay, Tamoghna Dutta, Achintya Kumar Chemical Physics We present a computationally efficient relativistic formulation of the equation-of-motion coupled-cluster method for the double electron attachment problem. In this work, the exact two-component Hamiltonian within the atomic mean-field approximation is employed, yielding results that are in close agreement with the corresponding four-component calculations. However, canonical DEA-EOM-CCSD calculations become prohibitively expensive for heavy elements and large basis sets due to the substantial memory requirements associated with complex 3p1h excitation manifold. To address this limitation, we introduce a state-specific frozen natural spinor basis that significantly reduces the virtual space through two controllable truncation thresholds. Furthermore, the use of Cholesky decomposition for the two-electron integrals provides an additional reduction in computational cost and memory. The performance of the proposed approach is demonstrated through calculations of double ionization potentials and excitation energies for group-12 and group-14 heavy elements. Vertical excitation energies for heavy chalcogen dimers are also presented. In addition, a range of diatomic spectroscopic constants is evaluated for group-13 halides. |
| title | A reduced-cost two-component relativistic equation-of-motion coupled cluster method for the double electron attachment problem |
| topic | Chemical Physics |
| url | https://arxiv.org/abs/2603.28441 |