Efficient evaluation of the Breit operator in the Pauli spinor basis

• DOI: 10.1063/5.0098828
• Publication Date: 2022-07-13T21:36:39Z
• Authors: Shichao Sun; Jordan Ehrman; Qiming Sun; Xiaosong Li
• Keywords: Momentum operator; Pauli exclusion principle

The frequency-independent Coulomb-Breit operator gives rise to the most accurate treatment of two-electron interaction in non-quantum-electrodynamics regime. Breit Coulomb gauge consists magnetic and contributions. high computational cost term limits application relativistic molecular calculations. In this work, we apply Pauli component integral-density matrix contraction scheme for with a maximum spin- separation scheme. We also present two different algorithms evaluating integrals. One is generalized Obara-Saika algorithm, where Laplace transformation used transform into Gaussian functions recursion reducing angular momentum. other algorithm second derivative evaluated Rys-quadrature. This work improves efficiency performing Dirac-Hartree-Fock variational systems. use formalism examine trends Periodic Table analyze contributions heavy-element complexes.