Superfície de energia potencial global e dinâmica molecular para o estado eletrônico fundamental do SiSH

Abstract

In this work we report the rst analytical global potential energy surface for the electronic ground state SSiH by means of electronic structure calculations with a function based on energies ab initio calculated at the Davidson-corrected multiple-reference con- guration interaction level ( MRCI) with aug-cc-pV(t+d)Z and aug-cc-pV(q+d)Z base sets and later with the full extrapolation base set (CBS). The analytical representation follows the methodology of expansion of many bodies of Aguado and Paniagua. A total of 2487 points ab initio were used to t the analytic function with 255 linear terms and 3 nonlinear terms for the 3-body term. The topological features as well as the reaction paths with the saddle points of the function are presented. A study of quasi-classical trajectories for the systems SH + Si → SSi + H and SiH + S → SSi + H are performed using the new function. The rst collision presents a barrier-type reaction with short interaction time in the region of the minimum forming the SiS product, an analysis of the trajectories and the rate constant for the reaction were presented. The second collision presents a reaction with longer interaction time in the minimum region forming the SiS product, an analysis was made regarding the interaction geometry to understand the type of reaction, the rate constant was also presented. The objective of this work is to present the global potential energy surface for the SSiH system and analyze the kinetic properties of the reactions forming the SiS from the dynamics of quasi-classical trajectories, product of both reactions is a species widely observed in star formation regions. around a sun-like protostar in the milky way: L1157- B1, SgrB2 and Orion KL.