Explicitly correlated Gaussian functions have been used to perform very accurate variational calculations for the ground states of Li7 and Li-7. The nuclear motion has been explicitly included in the calculations (i.e., they have been done without assuming the Born-Oppenheimer (BO) approximation). An approach based on the analytical energy gradient calculated with respect to the Gaussian exponential parameters was employed. This led to a noticeable improvement of the previously determined variational upper bound to the nonrelativistic energy of Li-. The Li energy obtained in the calculations matches those of the most accurate results obtained with Hylleraas functions. The finite-mass (non-BO) wave functions were used to calculate the α2 relativistic corrections (α=1c). With those corrections and the α3 and α4 corrections taken from Pachucki and Komasa [J. Chem. Phys. 125, 204304 (2006)], the electron affinity (EA) of Li7 was determined. It agrees very well with the most recent experimental EA.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry