
From:  Guillaume Larsen 
Subject:  [ESPResSo] constraints and nemd 
Date:  Thu, 25 Mar 2010 15:21:24 +0000 
dear all, i have several questions concerning the 'constraint plane cell' feature: 1) the definition of this constraint doesn't seem really clear to me, 'constraint plane cell x y z type id' the example from the manual: create an inﬁnite plane in z direction at z = 20.0 of type id 1, use: constraint plane cell 10 10 20 type 1to define a plane, one should need a normal vector and a position from origin, but here we only have 3 parameters x, y and z to configure. What do represent the '10' for x and y in the command. I want to define two planes: which values for x1,2 and y1,2 should I use to define the planes below? constraint plane cell $x1 $y1 $box_l_i type $wall_type > normal zdirection at z=$box_l_i constraint plane cell $x2 $y2 0 type $wall_type > normal zdirection at z=0 So far, i picked different values for x and y, but ESPResSo returns error messages about plane constraint violation (error 063) at warm up phase. 2)is it possible to use the tunable slip interaction command associated to a 'constraint wall' command? 3)I have been having problems recently with the use of the nemd feature, and i think the misuse of 'constraint plane cell' is the reason. The fact is that I want to use the nemd feature to compute the viscosity of the system. Two 'constraint plane cell' have to be defined before using the command 'nemd viscosity', is it right? Thank you in advance for your answers! best regards, Guillaume Commander un cadeau en ligne discrètement? Voir la solution offerte par Internet Explorer8 
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