IMPROVED QUANTUM MONTE-CARLO CALCULATION OF THE GROUND-STATE ENERGY OF THE HYDROGEN MOLECULE

We report an improved Green's function quantum Monte Carlo calculation of the nonrelativistic ground-state energy of the hydrogen molecule, without the use of the Born-Oppenheimer or any other adiabatic approximations. A more accurate trial function for importance sampling and the use of the exact cancellation method combine to yield an energy which is a factor of 10 more accurate than that of previous quantum Monte Carlo calculations. The energy is less accurate than that of recently improved analytic variational calculations. The calculated energy is -1.164 0239 ±0.000 0009 hartree. Expressed as the dissociation energy and corrected for relativistic and radiative effects, the result is 36 117.84±0.20 cm-1, a value in agreement with the most recent experimental value 36 118.11±0.08 cm-1 obtained by Balakrishnan et al. © 1995 American Institute of Physics.