Calculation of the deuterium electric field gradient in DF

We report theoretical results of the electric field gradient at the position of the deuterium nucleus in the DF molecule. The purpose of the calculation is the evaluation of a correction term to the expectation value of the electric field gradient with respect to a linear combination of atomic orbitals-molecular orbital self-consistent field (LCAO-MO SCF) function proposed by Ransil. Our method is based on a variation-perturbation method that was proposed previously. The expectation value of q_D⁰ (el) is q_D=-2.8964, the corrected value is q_D (el)=-2.9056, and the experimental value is q_D (exp)=-2.9241 (all values are expressed in terms of atomic units). The difference between our theoretical value and the experimental result is 0.6%.