 
Summary: Improved quantum Monte Carlo calculation of the groundstate energy
of the hydrogen molecule
Bin Chena)
and James B. Andersonb)
The Pennsylvania State University, University Park, Pennsylvania 16802
Received 30 August 1994; accepted 8 November 1994
We report an improved Green's function quantum Monte Carlo calculation of the nonrelativistic
groundstate energy of the hydrogen molecule, without the use of the BornOppenheimer 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.
I. INTRODUCTION
The hydrogen molecule H2 is a basic arena for the con
