 
Summary: Improved estimates of the total correlation energy in the ground state
of the water molecule
Arne Lu¨chow and James B. Anderson
Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
David Feller
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland,
Washington 99352
Received 1 October 1996; accepted 5 February 1997
Two new calculations of the electronic energy of the ground state of the water molecule yield
energies lower than those of any previously reported variational calculations. A fixednode quantum
Monte Carlo calculation gives 76.420 1 hartrees and an analytic variational calculation gives
76.4274 hartrees. These values lie only 17 and 11 mhartrees, respectively, above the
``experimental'' value. © 1997 American Institute of Physics. S00219606 97 007186
We report here two new calculations of very high accu
racy for the electronic energy of the ground state of the water
molecule. The energy given by a fixednode quantum Monte
Carlo calculation is 76.421(1) hartrees, a value lower than
any previously reported variational energy and only 0.017
hartrees above the experimentallyderived nonrelativistic,
infinitemass value of 76.438(3) hartrees. The energy
