Summary: Intermolecular forces and fixed-node diffusion Monte Carlo: A brute force
test of accuracies for He2 and He­LiH
Massimo Mellaa)
Dipartimento di Chimica Fisica ed Elettrochimica, Universita' degli Studi di Milano, via Golgi 19,
20133 Milano, Italy
James B. Andersonb)
Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
Received 8 July 2003; accepted 31 July 2003
The accuracy of the fixed-node approximation and diffusion Monte Carlo method in computing the
interaction energy of van der Waals systems was investigated. Tests were carried out by simulating
the electronic structures of He2 and He­LiH. These two systems were chosen as representative of
two fundamentally different interactions, namely the weak dispersion forces in He2 and the dipole/
induced­dipole interaction in He­LiH. The results for both systems are in excellent agreement with
``state of the art'' calculations, thereby indicating a high accuracy for the fixed-node approximation.
Also, our interaction energies for He­LiH indicate that the coupled cluster single double triple
method Taylor and Hinde, J. Chem. Phys. 111, 973 1999 gives an accurate prediction of the
interaction potential for that system. © 2003 American Institute of Physics.
DOI: 10.1063/1.1612479
The accurate description of interaction potentials is of
paramount importance in rationalizing and predicting the

Source: Anderson, James B. - Department of Chemistry, Pennsylvania State University

Collections: Chemistry