Time Recovery for a Complex Process Using Accelerated Dynamics

S. A. PAZ; C NARAMBUENA, E.P.M. LEIVA

JOURNAL OF CHEMICAL THEORY AND COMPUTATION

AMER CHEMICAL SOC

Lugar: Washington; Año: 2015 vol. 11 p. 1725 - 1734

1549-9618

The hyperdynamics method (HD) developed by Voter [J. Chem. Phys. 106 (1996)11] sets the theoretical basis to construct an accelerated simulation scheme that holds the time scale information. Since HD is based on transition state theory, pseudo-equilibrium condition (PEC) must be satisfied before any system in a trapped state may be accelerated. As the system evolves, many trapped states may appear and the PEC must be assumed in each one to accelerate the escape. However, since the system evolution is a priori unknown, the PEC cannot be permanently assumed as true.Furthermore, the different parameters of the bias function used may need drastic recalibration during this evolution. To overcome this problems we present a general scheme to switch between HD and conventional molecular dynamics (MD) in an automatic fashion during the simulation. To decide when HD should start and finish, criteria based on the energetic properties of the system are introduced. On the other hand, a very simple bias function is proposed leading to a straightforward on-the-fly set up of the required parameters. A way to measure the quality of the simulation is proposed.The efficiency of the present hybrid HD-MD method is tested for a two-dimensional model potential and for the coalescence process of two nanoparticles. In spite of the important complexity of the latter system (165 degrees of freedoms), some relevant mechanistic properties were recovered within the present method.