Izuchyeniye elyektronnoi{cyrillic, short} struktury molyekul, Kh. - Ground state for adenine, cytosine, guanine and thyamine - Osnovnoye sostoyaniye dlya adyenina, tsistozina, guanina i tiamina

Abstract

All electrons SCF-LCAO-MO computations for adenine, cytosine, guanine and thyamine are reported. In addition, to compute the total energies and wave functions we have computed the relative gross charges and the dipole moment. Analysis of the orbital energy for the inner shell indicates that there are three effects which govern the orbital energies splitting for inner shell a) the gross charge, or ionicity degree, of the atom in consideration, b) its valency state, c) the neighbor atoms ionicities. The first two effects are sufficient for determining the relative location of the inner shell as well as for estimating the extrema of the splitting of the inner shell electrons of a given type of atoms. The gross charge population was used to determine the overall flow of the σ and π charge transfer. It was found that the charge transfer flow requires direct consideration of at least next nearest neighbors to be explained. In addition, it was found that simple π electron considerations could lead to not only quantitative but even to qualitative erroneous prediction about the electronic charge distribution. For example, an atom can be positively charged, if one considers only the π electrons, and the same atom can be negatively charged, if one considers only the σ electrons. Therefore, we reiterate on the necessity of all electron computations not only for quantitative but even for qualitative studies of the electronic structure in molecules. © 1969 with the authors.