Dinâmica molecular da reação de abstração de hidrogênio no MH4 (M = C, Si, Ge, Sn) por átomos de H, F, Cl e I induzida por pulso de laser de femtosegundos

Abstract

In this study, it has been carried out quantum molecular dynamics simulations for the hydrogen abstraction reaction from methane, silane, germane and stannane by H, F, Cl and I atoms and being or not being induced by femtosecond laser pulses with the aim to favor the dissociation of the M-H (M = C, Si, Ge and Sn). All the simulations have been performed using a simulation scheme based on ab initio calculations of molecular dynamics, where the motion of the atomic nuclei is described classically while the electrons are treated quantically by the Density Functional Theory (DFT). The results of the molecular dynamics simulations for the hydrogen abstraction reaction from methane, that is a very inert molecule, show that only the fluorine atom is able to promote the dissociation of the C-H bond. For the simulations performed in the presence of the electromagnetic radiation, it was possible to observe that the femtosecond laser pulse could induce the hydrogen abstraction from methane when the reaction occurs with the hydrogen or fluorine atom. The results of the molecular dynamics simulations for the hydrogen abstraction reaction from silane show that also the fluorine as the hydrogen atoms are able to dissociate effectively the Si-H bond in silane. In the case of the hydrogen abstraction from silane by the chlorine atom, the effective Si-H dissociation does not happen. In the simulations including the pulsed electromagnetic radiation, it is observed that it was possible to favor even more the hydrogen abstraction reaction from silane by the hydrogen and fluorine atoms, moreover, it was possible to turn effective the dissociation of the Si-H bond by the chlorine atom. The GeH4 and SnH4 molecules could be easily dissociated by the hydrogen, fluorine and chlorine atoms. About the iodine atom, it was not able to promote the hydrogen abstraction reaction in germane and stannane, even in the presence of the femtosecond laser pulse.