Relativistic exact two-component coupled-cluster calculations of electronic g-factors for heavy-atom-containing molecules pertinent to search of new physics

Abstract

Exact two-component (X2C) coupled-cluster calculations of electronic g-factors for heavy-atom-containing small molecules pertinent to search of new physics beyond the standard model (BSM) is reported. A magnetic-field-dependent unitary transformation of the Dirac Hamiltonian has been adopted to enable a simple inclusion of the quantum electrodynamics correction to the free-electron g-factor in the four-component formulation. The X2C transformation is subsequently employed to eliminate the positronic degrees of freedom to enhance computational efficiency without significant loss of accuracy. The relationship of the present scheme to alternative four- and two-component formulations is discussed. To demonstrate the accuracy and usefulness of the present X2C scheme, we report coupled-cluster calculations for electronic g-factors of representative heavy-metal-containing small molecules including those relevant to precision spectroscopic search of BSM physics.