======= Metadynamics =======
===== Introduction =====

**Metadynamics** is a method that allows the acceleration of rare events and estimation of the free energy of a system undergoing conformational transitions.  

In the following exercise, we will explore the dynamic equilibrium between formic acid and water molecules at the rutile (110) TiO$_2$ surface. For more information about the keywords used in the input files, refer to [[https://manual.cp2k.org/trunk/CP2K_INPUT/MOTION/FREE_ENERGY/METADYN.html|METADYN]]. 

The tasks to be performed are:
  * Set up and run preliminary simulations to understand the dynamics of formic acid and water on TiO$_2$ obtained from DFT-based Born-Oppenheimer MD simulations;
  * Metadynamics simulation to trigger the replacement of an adsorbed formate/formic acid by a water molecule by following changes of two different collective variables.

===== First task: dynamics of formic acid and water molecules on rutile (110) =====