Date: Thu Jul 08 2004 - 10:30:31 CDT
These are the lengths of the sides of the unit cell. So if your unit cell were
100Ax50Ax60A then the cellBasisVectors would be
cellBasisVector1 = 100,0,0
cellBasisVector2 = 0,50,0
cellBasisVector3 = 0,0,60
An important point is to make sure that your system is centred on the origin:
NAMD assumes this.
> I was wondering if someone could confirm if my understanding is right.
> When setting the cellBasisVector1, cellBasisVector2, cellBasisVector3 for
> Periodic Boundary conditions in the NAMD config file:
> cellBasisVector1 = x,0,0
> cellBasisVector2 = 0,y,0
> cellBasisVector3 = 0,0,z
> The x,y,z are the minimum OR maximum values obtained by running the command
> in VMD:
> > set everyone [atomselect top all]
> > measure minmax $everyone
> Can someone please confirm if this is correct?
> The tutorial Statistical Mechanics of Proteins doesn't explicitly indicate
> that the x,y,z values should be min or max - infact it doesn't tell you how
> to obtain the x,y,z values.
> The tutorial infact says:
> "Three periodic cell basis vectors are to be specified to give the periodic
> cell its shape and size. They are cellBasisVector1 , cellBasisVector2, and
> cellBasisVector3 . In this file, each vector is perpendicular to the other
> two, as indicated by a single x, y, or z value being specified by each. For
> instance, cellBasisVector1 is x = 42Å, y = 0Å, z = 0Å. With each vector
> perpendicular, a rectangular 3-D box is formed."
> Where they came up with the value for x,y,z is not explicitly indicated.
> But if my understanding is correct I believe it should be the min max
-- Philip Fowler, PhD Student Centre for Computational Science, UCL Chemistry
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