It is pointed out that the rms fluctuation of the local energy encountered in variational Monte Carlo calculations, together with the expected energy, can be used to produce a nontrivial lower bound on the ground-state energies of atoms and molecules. This lower bound has the desirable properties of general accessibility (via Monte Carlo calculations) and linear sensitivity to deviations of the trial wave function from the exact wave function. These qualities of accessibility and sensitivity are demonstrated with numerical data obtained from recent Monte Carlo calculations on the helium atom and the hydride ion.

• Received 30 January 1989

DOI:https://doi.org/10.1103/PhysRevA.40.6077