[Quantum-chemical polyempirical study of the polymorphism of Watson-Crick pairing of nitrous bases].

The plurality of the geometry of complementary AT- and GC-pairs of nucleic acid nitrous bases was substantiated in terms of the semiempirical scheme of modified neglection of the differential diatomic overlap. A sixfold polymorphism of the Watson-Crick pairing was confirmed, which was established previously on the basis of simple PCILO conformational calculation. For purposes of experimental spectral identification of arising noncoplanar structures, the range of expected values of their inertial defects was determined.