On Fri, 09 Apr 2010 11:33:00 +0200, Ngoc Linh Nguyen <nnlinh at sissa.it> wrote: > In that > case, the diffusion of molecules will be presented, and it can be seen > as a picture that the molecules are moving parallelly to the plane's > substrate to find out the activate sites. And of course, the center of > mass is not changed at all belong to Oz component.
yes, but the molecule cannot rotate if you fix the z components of all its atoms: it is a condition sufficient to fix the center of mass, but not necessary. cheers -- Lorenzo Paulatto *** Note: my affiliation has changed! please send future correspondence to: <Lorenzo.Paulatto at impmc.upmc.fr> *** post-doc @ IMPMC/UPMC - Universit? Paris 6 phone: +33 (0)1 44 27 74 89 www: http://www-int.impmc.upmc.fr/~paulatto/ previously: phd student @ SISSA & DEMOCRITOS (Trieste) phone: +39 040 3787 511 www: http://people.sissa.it/~paulatto/
