In the first chapter we present numerical methods to describe termally activated processes and particularly the nudged elastic band method (NEB) to find minimum energy paths (MEPs) on potential energy surface (PES).
In the second chapter we study a case that demonstrates by means of ab-initio calculations that steps are more reactive than plain surfaces. Water dissociation activation barrier is computed lower on stepped Pt(211) and
Pt(311) surfaces respect to clean Pt(111) surface.
In the third chapter we investigate water formation on Rhodium surface at high oxygen coverage with the aim to explain an interesting experiment performed at ELETTRA - Trieste.
In the appendix A we make a brief discussion about density functionals and their drawbacks in correctly describing chemical reactions. In the appendix B we briefly describe a parallel work of development and code maintenance of PWSCF code of suite ESPRESSO [24] with the purpose of adding exact exchange and hybrid functionals to the code
