Electron affinity of hydrogen, deuterium, and tritium: A nonadiabatic variational calculation using explicitly correlated Gaussian basis functions

Nonadiabatic variational calculations for the anion ground state energies, mass shifts, and electron affinities of Hydrogen, Deuterium and Tritium are reported. Electron affinities values are 6083.0994, 6086.7137, and 6087.9168 cm^-1 for Hydrogen, Deuterium, and Tritium, respectively. These results were obtained using a basis of explicitly correlated Gaussians. Exact nonrelativistic energy bounds are carefully predicted: E(H^-) = -0.5 274 458 811, E(D^-) = -0.5 275 983 247, and E(T^-) = -0.5 276 490 482 in hartree energy units. It is shown that these new bounds cannot be obtained using the infinite nuclear mass approximation plus Rydberg scaling and the usual first order mass polarization correction.