Showing papers by "Enrico Clementi published in 1971"

Study of the Electronic Structure of Molecules. XIV. Point Charge Perturbation on Periodic Systems

Abstract: We have simulated the perturbation involved by a solvent (or by other periodic perturbants) on a polymer (polyethylene) and we have analyzed (1) the effect of the perturbation on the energy bands of the polymer and (2) the internal charge transfer occurring on the polymer as a response to the external perturbation. The band structure is computed in the tight binding approximation using a self‐consistent field model originally proposed by Ladik and subsequently improved and programmed by Andre. The model is an ab initio model, aimed at Hartree–Fock solutions for the band structure of periodic systems. All the many center integrals of coulomb and exchange type are accurately computed (the computation is an all‐electron computation, and with no approximation for the atomic potential of the atoms in the unit cell). We have found that by surrounding the polymer with positive or negative point charges, the entire band system raises or lowers its entire energy spectrum. The band structure (and the energy gap) wa...