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Some new results in the quantum mechanical investigation of DNa
Author(s) -
Ladik J.,
Otto P.,
Förner W.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560240710
Subject(s) - chemistry , basis set , atomic orbital , ab initio , polynucleotide , charge (physics) , molecular orbital , hartree–fock method , molecular physics , computational chemistry , atomic physics , quantum mechanics , physics , molecule , density functional theory , biochemistry , electron
Abstract As a first step in testing the possibility of correlation calculations of extended systems using localized orbitals, localization of the canonical Hartree‐Fock orbitals of the four nucleotide bases was performed. The results show an excellent localization of the occupied orbitals and a rather good one for the virtuals (both for the σ‐ and π‐orbitals). Interaction energy calculations of the stacked nucleotide bases show a few kcals/mol repulsion at the Hartree‐Fock level, but they become attractive (again a few kcals/mol) if dispersion energy computed with the aid of London's formula is added. The internal charge transfer of ˜0.2 e from sugar to the nucleotide base (C, T, or A) found in large‐scale ab initio homopolynucleotide calculations raises the question of whether there are free charge carriers in DNA B. Though in the Hartree‐Fock level the answer is negative, one cannot rule out this possibility if, using a high‐quality basis set, correlated band structures (using an unproved version of the electronic polaron model) will be computed. Interaction energy calculations between a polyglycine chain in different conformation and polynucleotide chains show a few kcals/mol attraction per base and glycine unit and a very small (a fraction of a kcal/mol) additional attraction due to the dispersion correction.