Analytic Evaluation of Energy First Derivatives for Cholesky Decomposition-Based Relativistic Two-Component Coupled-Cluster Methods

Analytic evaluation of first-order properties for the Cholesky decomposition (CD)-based relativistic two-component coupled-cluster singles and doubles (CCSD) and equation-of-motion CCSD (EOM-CCSD) methods is reported. The CD-based implementation significantly improves the efficiency in handling two-electron integrals involving frozen orbitals and reduces the storage requirement for the two-electron density matrices in analytic derivative calculations. Benchmark calculations of dipole moments, electric field gradients, and molecular sensitivity factors for nuclear Schiff moments show that a modest Cholesky threshold of 10–4 provides accurate results. Calculations for Mössbauer spectroscopy parameters of gold-containing complexes are reported to demonstrate the applicability of the present implementation to medium-sized molecules containing heavy atoms.