ИСТИНА

Modelling of biochemical systems at the molecular level has some methodic difficulties. To understand the processes taking place in systems with xenon accurate calculations of weak dispersion interactions are needed. Density functional theory combined with QM/MM approach seems to be the most comprehensible method for modelling of complex biosystems. We were investigated systems, which contain xenon atoms and aromatic molecules (phenol, tyrosine, tryptophan and other). The calculations of geometry and binding energies were carried out with DFT with addition of empirical correction on dispersion intercation by Grimme [1], implemented in program package GAMESS(US). We were examined a set of exchange-correlation functionals (B3LYP, BLYP, PBEOP, X3LYP, M05-2X, PBEVWN and other) to reproduce standard values, which were obtained from perturbation theory MP2 calculations with aug–cc–pVTZ basis set. It was shown that the calculations with B97-D functional and 6–31G* basis set provide good geometrical structures and binding energies of main isomer (phenol+xenon). At the same time some local minima not corresponding to ab initio MP2 calculations were presented. Using of larger basis set (cc–pVTZ) instead of small (6–31G*) did not improve situation much. That problem shows that using the Grimme's technique is limited. Thus for modelling of biochemical systems using DFT method, choosing of initial geometries is required and admissible description of weak dispersion interaction is expected. The authors thank RCC of MSU for providing computational resources. The work was carried out with financial support of RFBR. Project number 10-03-00139. Antony J., Grimme S. Phys. Chem. Chem. Phys., 2006, 8, 5287-5293