ИСТИНА

The knowledge of force fields of different molecular conformations is reliable when constructing force constant matrices of complicated biomolecules. The force constant matrices can be considered within different models varying from the complete identical to the quite different matrices for different conformers. The construction of sufficiently simple and adequate physical model that can be applied to a wide range of compounds with hindered internal rotation is very complicated problem due to a limited number of experimental data directly related to the force field parameters of different conformers. Determination of force constants from experimental data requires a solving of the so-called inverse vibrational problem related to the ill-posed problems and characterized by non-uniqueness and instability of its solution as well as by possible incompatibility within harmonic model of experimental data available. These difficulties of solving the inverse vibrational problem are overcome by using stable numerical methods for the joint treatment of experimental and quantum mechanical data when ab initio or DFT data serve as a stabilizer of a solution. It allows us to narrow the class of possible solutions and obtain the so-called regularized quantum mechanical force field (expressed in terms of any system of generalized coordinates.