Re: MD or MC

[blonski at.at alumina.rutgers.edu (Slawomir Blonski)]

 Q:
 > 	   Which one, MD or MC, you will select if CPU time-constraint
 >    is imposed ?
 A:
 > The choice between MD and MC depends not on your CPU time allocation,
 > but on the problem you want to solve.
 There is a class of Monte Carlo simulations which can be directly compared
 with molecular dynamics. These are the MC studies of time-dependent phenomena.
 See for example works on polymer reptation by Kurt Binder or on biopolymers
 by team Skolnick - Kolinski. In such an approach, a new MC configuration is
 formed from the previous one (after being accepted with Metropolis criterion).
 This may be assumed to be equivalent to a time evolution of the system. Because
 changes in the system between consecutive MC configurations are greater than
 after a single MD time step, one can treat the MC step as a time period much
 longer than the MD time step. In this way, the time-dependent MC simulations
 extend longer in time than the MD with the same number of steps, although
 the exact length of the MC time step is hard to estimate and MC gives only
 positions of the particles, but not the momenta. However, MC may be preferred
 over MD, if one simulates large systems with long relaxation times which are
 beyond reach of current computers.
 Slawomir Blonski
 PS. I use molecular dynamics.