[gmx-users] BD and SD equations

Marcelo A. Carignano cari at northwestern.edu
Fri Jul 8 17:36:00 CEST 2011

Hi all,

Stochastic dynamics is described in section 3.8 of the Manual (v. 4.5)
Equation 3.108 is dimensionally incorrect, or at least I cannot  
understand it.
Left hand side is a force, and the first term on the right hand side  
has a missing length in the numerator to be a force.
This is according to the definition of xi, right below the equation,  
as having units of 1/ps.

Brownian dynamics, described in section 3.9, also has a problem  
(again, in my opinion)
gamma is defined as mass/xi, but it is using gamma=mass*xi that we can  
recover the two terms of the SD case
(still with the wrong dimensions)

Could anyone clarify this to me? Many thanks

M. Carignano

More information about the gromacs.org_gmx-users mailing list