Gauge-origin independent multiconfigurational self-consistent-field theory for vibrational circular dichroism

Abstract

Multiconfigurational self-consistent-field (MCSCF) theory is presented for the gauge-origin independent calculation of vibrational circular dichroism. Origin independence is attained by the use of London atomic orbitals (LAO). MCSCF calculations on ammonia and its isotopomer NHDT demonstrate that atomic axial tensors and vibrational rotational strengths converge fast with the size of the basis set when LAOs are used. The correlation effects are significant both for the atomic tensors and the vibrational rotational strengths even for the single configuration dominated NHDT molecule.