"Permutationally Invariant Polynomial Basis for Molecular Energy Surface Fitting via Monomial Symmetrization"
Z. Xie and J. M. Bowman
Journal of Chemical Theory and Computation, vol. 6, no. 1, , pp. 26-34. Also Preprint ANL/MCS-P1674-0909
Preprint Version: [pdf]
We describe a procedure to develop a fitting basis for molecular potential energy surfaces (PES) that is invariant with respect to permutation of like atoms. The method is based on a straightforward symmetrization of a primitive monomial basis and is illustrated for several classes of molecules. A numerically efficient method to evaluate the resulting expression for the PES is also described. The fitting basis is used to obtain a new PES for H3O+ based on roughly 62 000 ab initio energies.