Finding saddle points on free energy surfaces

Shiga, Motoyuki

no journal, , 

In general, there are many ways of free energy calculation using molecular simulation. For instance, metadynamics and mean force dynamics methods are known for the purpose of exploring free energy landscapes. However, in reactive systems, the number of channels leading to the reactions is small, so it is not always necessary to search the entire surface of the free energy landscape. It is often enough if the position and height of the stationary point (minimum and saddle points) on the free energy surface are accurately determined. Therefore, we propose a new method for saddle point search on multidimensional free energy surface by a new gentlest ascent method based on numerical evaluation of free energy second derivative. In particular, we show that statistical sampling can be accelerated, and accurate evaluation of free energy barriers is possible.