One-Center Expansion Wavefunctions for CH3−, CH4, and CH5+

Abstract

One-center expansion (OCE) wavefunctions for the species CHa-, C~, and CH6+ are presented. These wavefunctions are expressed by configuration interaction of the singly excited states of a closed-shell ground state. The basis set consists of STO's through 1=4, belonging to the irreducible representations spanned by the u-bonding representation. In addition the calculations on CHa-and CH6+ were done as a function of nuclear geometry. These calculations indicate that CHa-has a D3h configuration rather than a Cav configuration. The molecular configuration of CH6+ was indicated to be Dah rather than Ch or Ca..The ground-state energies of CHs-, Ca., and CH6+ were calculated to be -39.236, -39.859, and -40.036 a.u., respectively. The proton affinity of methane is calculated to be approximately 5 eV.

New Landscape of Electron-Pair Bonding: Covalent, Ionic, and Charge-Shift Bonds

“…Using MO theory, it is possible to transform the delocalized canonical MOs to a set of localized MOs (LMOs) that describe two-center bonds (for pioneering localization methods, see [32][33][34][35][36][37]). The LMOs retrieve the covalent-ionic superposition scheme as follows: The electron-pair bond is the LMO itself, while the covalent-ionic superposition can be quantified from the charge polarization of the LMO; namely, the relative size of the coefficients of the hybrids of the contributing fragments to the LMO determines the bond polarity.…”

Potential energy surfaces of CH5+by non-empirical calculations

“…The calculations [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] that have been performed on the species CH5 + range in sophistication from the extended Hiickel method to non-empirical calculations using a gaussian basis [4,6,[15][16][17]. The semi-empirical calculations give some details of the potential energy surface relevant to the kinetics of hydrogen exchange or abstraction in this simple system [3,5].…”