ИСТИНА

The transition energy S0-S1 and other properties of 2-cyano-5-(4-dimethylaminophenyl)penta-2,4-dienoic acid (PD) in a frozen aqueous solutions are calculated by using Time Dependent Density Functional Theory (TDDFT). Solvent effects were treated within different solvation models, such as polarized continuum model (PCM), effective fragments potential (EFP) approximation and explicit introduction of 113 water molecules, which form two layers of the solvation shell. The PBE0 functional and 6-31G* basis set are used. The red shift of the S0-S1 absorption band is predicted within all used solvation models. Value of transition energy shift in the PCM model is reduced to 420nm towards isolated molecule (393nm); maximum value of transition energy shift (427nm) holds for dye surrounded by 113 explicit water molecules, the geometry of the system obtained by optimization of cluster «PD*113H2O» using EFP approximation. Contribution of geometric relaxation and redistribution of electron density in the transition (S0-S1) energy shift are evaluated, as well as the extent of its penetration into the solvation shell. This work was supported by the program № 24 of the RAS Presidium