Noncovalent Interaction of Carbon, Silicon, and Germanium Atoms

The noncovalent interaction potentials for homo- and heteroatomic pairs of carbon, silicon, and germanium without the formation of valence chemical bonds are calculated from first principles (electron gas approximation). The calculations take into account the coulomb, kinetic, exchange, and correlation contributions to the interaction energy. The electron density is set taking into account the shell structure of atoms in the Hartree–Fock approximation. The parameters of the Lennard-Jones and Morse potentials and the constants of the dispersion interaction are calculated for all cases. It is shown that for noncovalent interaction the known empirical rules of the Lorentz–Berthelot combination for potential parameters are not always fulfilled. Based on the calculations, a new generalized potential is proposed that can be used in molecular dynamics and Monte Carlo simulations, as well as in constructing equations of state. The second virial coefficient for monatomic carbon vapor are is calculated.