multiple time stepping in namd: Query

Date: Tue Mar 27 2007 - 14:54:33 CDT

      I read from 2005 article on NAMD that it implements multiple time steps for integration scheme. Now my question is: Is it neccessary that that inner, middle and outer time steps be integer multiples of each other in the sense: I read we can use (1fs+1fs+3fs) when no constraints on H-atom and further can increase it to (2+2+4)fs with constraints on H-atom. But can i use (0.7+1+3)fs time step for some calculation. Further confusion is if bonded force calculations are every 0.7fs then how does algorithm handles 1fs middle and 3fs outer time steps when they are not multiples of 0.7fs. Or these three are indepedent of each other and calculated independently?

Any help/insights is appreciated.


Harish Vashisth (Ph.D Candidate)
CAT-361,Chemical & Biological Engg.
Drexel University, Philadelphia, PA
office: 215-895-5823

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