Configuration dependence of hopping matrix elements in the Anderson model

In ab initio calculations of the hopping matrix element $V$ in the Anderson model, it is found that $V^2$ may vary by a factor of 2-8 for Mn, Ce, and U compounds when different relevant configurations are used. We give a prescription for which configuration to use in an ab initio calculation of $V$, and we make a corresponding modification of the hopping term in the Anderson model, which can easily be implemented in methods for solving the model. We discuss how this influences the calculated properties of Ce compounds.