Second Quantization and the Hellmann-Feynman Theorem

Abstract

In the preceding chapters we have seen the advantages of the second quantized approach rather from the formalistic point of view. Here we take another standpoint and show an example where second quantization involves a somewhat different interpretation of the results. The example will be somewhat peculiar (Surján et al. 1988): we shall study the significance of the Hellmann-Feynman theorem in evaluating the first derivatives of the energy, which is topical in the field of optimizing molecular geometries, exponents of basis orbitals, etc.