Multi-scale Simulations of Dynamics of Chemical Reactions
The commonly used technique for a computational researcher to study the reaction mechanism involves the application of quantum-chemical procedures such as density functional theory (DFT) to construct potential surfaces describing the relative energies of reactants, intermediates and transition states. Statistical mechanics is then used to obtain relative free energies for these species. This approach sometimes referred to as the use of ‘static’ geometry optimization calculations, can be carried out either in the gas phase or in an “artificial” continuum solvent field. The motion of atoms leading to reaction is not treated explicitly, but through the use of an approximate dynamic theory such as transition state theory. However, such static calculations only treat the dynamics of the reaction in an approximate way. Also, the influence of the chemical environment is mostly neglected. Classical molecular dynamics (MD) methods, in contrast, are able to consider a much larger environment and to treat time-resolved effects, but as they rely on molecular mechanic force-fields, they are unfortunately not applicable to systems involving the formation and breaking of chemical bonds. Here, particular attention is given to develop reactive force fields to investigate reaction dynamics.