Relativistic Internally Contracted Multireference Electron Correlation Methods

Abstract

We report internally contracted relativistic multireference configuration interaction (ic-MRCI), complete active space second-order perturbation (CASPT2), and strongly contracted n-electron valence state perturbation theory (NEVPT2) on the basis of the four-component Dirac Hamiltonian, enabling accurate simulations of relativistic, quasi-degenerate electronic structure of molecules containing transition-metal and heavy elements. Our derivation and implementation of ic-MRCI and CASPT2 are based on an automatic code generator that translates second-quantized ansatze to tensor-based equations, and to efficient computer code. NEVPT2 is derived and implemented manually. The rovibrational transition energies and absorption spectra of HI and TlH are presented to demonstrate the accuracy of these methods.

References in corpus (3)

• Automatic code generation enables nuclear gradient computations for fully internally contracted multireference theory
• Four-Component Density Matrix Renormalization Group
• Exomol molecular line lists VI: A high temperature line list for Phosphorus Nitride

Cited by in corpus (11)

• BAGEL: Brilliantly Advanced General Electronic-structure Library
• Perspective: Essentials of Relativistic Quantum Chemistry
• One-step treatment of spin-orbit coupling and electron correlation in large active spaces
• Large-scale relativistic complete active space self-consistent field with robust convergence
• Analytical Gradient Theory for Strongly Contracted (SC-) and Partially Contracted (PC-) N-Electron Valence State Perturbation Theory (NEVPT2)
• SOiCI and iCISO: Combining iterative configuration interaction with spin-orbit coupling in two ways
• Zero-Field Splitting Parameters from Four-Component Relativistic Methods
• Towards accurate spin-orbit splittings from relativistic multireference electronic structure theory
• Consistent Second-Order Treatment of Spin-Orbit Coupling and Dynamic Correlation in Quasidegenerate N-Electron Valence Perturbation Theory
• An efficient solver for large structured eigenvalue problems in relativistic quantum chemistry
• Numerically Exact Configuration Interaction at Quadrillion-Determinant Scale