A full-configuration interaction nuclear orbital method to study doped 3HeN clusters (N≤4)

An efficient full configuration interaction (FCI) treatment, based on the Jacobi-Davidson algorithm, is developed in order to study small doped He-3(N) clusters. The state of each He atom in a given cluster is described by a set of wave-functions which by extention of the quantum-chemistry notation are caller here nuclear orbitals. The FCI treatment is applied to the calculation of binding energies and helium natural orbitals of He-3(N)center dot Br-2(X) complexes. In agreement with our previous calculations using a Hartree-Fock approach [Phys. Rev. Lett. 93, 053401 (2004)], in which the He-He interaction is modified at small distances to account for short-range correlation effects, the lowest-energy states of each multiplet are found to be very close in energy. The natural orbital analysis, in turn, indicates the adequacy of the nuclear orbital approach in these systems. (c) 2006 American Institute of Physics.