The reaction of F atoms with ·CH_2SH radical has been studied by using quantum chemistry ab initio and density function theory (DFT) calculations along the potential energy surface. The optimized geometrical parameters, vibrational frequencies ad zero-point vibrational energies (ZPVE) of all species were obtained at the B3LYP/6-311G theoretical level. The total energies were worked out using the B3LYP/6-311 + G(2df, pd)//B3LYP/6-311G method. In addition, the G3 energies of reactants and products were also obtained. The results indicate that the reaction proceeds through addition of a F atom to CH_2SH by either F-C or F-S combination to form initial complexes, followed by H(4) migration to form methyl radical CH_3·, which rotates around main C-S bond to result in combination of H(4) and F. Formation of HF and CH_2S is the most probable reaction chanel with the exothermic heats of 396.94 kJ/mol (G3) and 370.7 kJ/mol (DFT) respectively. Furthermore, the enthalpy of formation of CH_2SH was deduced to be 146.44 kJ/mol (DFT) and 167.36 kJ/mol (G3), which are in agreement with existing experimental and theoretical values.

Key words: AB INITIO CALCULATION, METHANE P, SULFUR COMPOUNDS, FORMATION HEAT