A-T -12.1: C-G -21.0 kcal/mol
||C.F. Guerra, F.M. Bickelhaupt, J.G. Snijders and E.J. Baerends. Hydrogen Bonding in DNA Base Pairs:? Reconciliation of Theory and Experiment J. Am. Chem. Soc. 2000, 122, 4117-4128 DOI: 10.1021/ja993262d abstract & p.4119 right column bottom paragraph & p.1421 table 1 and table 2
||Yanson IK, Teplitsky AB, Sukhodub LF. Experimental studies of molecular interactions between nitrogen bases of nucleic acids. Biopolymers. 1979 May18(5):1149-70.PubMed ID435611
||"Up till now, there has been a significant disagreement between theory and experiment regarding hydrogen bond lengths in Watson-Crick base pairs. To investigate the possible sources of this discrepancy, [researchers] have studied numerous model systems for adenine-thymine (AT) and guanine-cytosine (GC) base pairs at various levels (i.e., BP86, PW91, and BLYP) of nonlocal density functional theory (DFT) in combination with different Slater-type orbital (STO) basis sets."
||"Best agreement with available gas-phase experimental A-T
and G-C bond enthalpies (-12.1 and -21.0 kcal/mol) is obtained at the BP86/TZ2P level, which (for 298 K)
yields -11.8 and -23.8 kcal/mol...Tables 1 and 2 show that BP86/TZ2P provides A-T and
G-C bond enthalpies (-11.8 and -23.8 kcal/mol) that agree
within 0.3 and 2.8 kcal/mol, respectively, with the corresponding
gas-phase experimental [primary source] values (-12.1 and -21.0 kcal/mol)."