NEW ASPECTS IN THE CALCULATION OF ELECTRONIC MOMENTUM PROPERTIES - ANALL-QUANTUM STUDY

The electronic properties of the C6H6 and C6D6 molecules have been stu died by an all-quantum approach, where the classical and quantum degre es of freedom of the nuclei are taken into account in the evaluation o f electronic expectation values. In the all-quantum approach suggested a Feynman path integral Monte Carlo (PIMC) formalism has been linked to an electronic ab initio Hamiltonian. The electronic expectation val ues have been calculated as averages over the manifold of nuclear conf igurations populated in thermal equilibrium This theoretical setup lea ds to electronic expectation values that depend on the temperature and on the mass of the nuclei. The ensemble averaged electronic propertie s differ sizeably from the results derived on the basis of a single nu clear configuration of minimum energy. This behaviour should have phys ical implications for the theoretical calculation of electronic moment um properties such as Compton profiles, reciprocal form factors, etc. We describe an error source in the theoretical determination of electr onic momentum properties which has not been commented so far.