Calculation of the total energy of a diatomic molecule in the first order of perturbation theory taking into account the Pauli principle and plasma oscillations of atomic electrons

TL;DR

This paper calculates the total energy of diatomic molecules in the first order of perturbation theory, incorporating the Pauli principle and plasma oscillations of electrons, with numerical results for nitrogen and fluorine.

Contribution

It introduces a method to include plasma oscillations and the Pauli principle in perturbation calculations of diatomic molecule energies, providing new insights into molecular elastic constants.

Findings

Total energy calculated for nitrogen and fluorine molecules.

Plasma oscillations influence the potential energy surface.

Determination of the elastic constant from the second derivative of potential energy.

Abstract

In the first order of perturbation theory, the total energy of a diatomic molecule in the ground state is calculated taking into account the Pauli principle and plasma oscillations of atomic electrons. The Fourier component of the potential energy of interaction of an atom with an atom has the form of a polynomial of the fourth degree of the atomic form factor. Numerical calculation is performed for the atomic form factor in the approximation of hydrogen-like wave functions, which approximate the solution of the Hartree-Fock equation for an isolated atom. It is shown that taking into account the plasma oscillations of atomic electrons leads to a self-consistent system of equations, the numerical solution of which makes it possible to determine the elastic constant, that is, the value of the second derivative at the minimum of the potential energy of the molecule. The total energy for nitrogen and fluorine molecules is calculated.