dipole for united atom with OOPSE------Many thanks

[Dan Gezelter]

>  1.) You mentioned that in DUFF.frc, the dipole moment of the HEAD
>       is along Z-axis.  Is it true for all dipoles?  And, the 
> quaternions describe
>       the orientation of dipoles, the relative orientation of dipole and 
> the nonspherical
>       united atoms is specified by the moment of inertia tensor. Am I 
> right?

Dipoles are always along the body-fixed z-axis of that atom type, and
the quaternions in the .in and .dump files describe the orientation of
this body-fixed frame in the lab frame.  The moments of inertia are
usually specified by the diagonal elements in the body-fixed frame.

>  2.) I tested the parallel version. I run it for Argon, 500 atoms on two 
> processors.
>       It's slower than serial calculation.  

This is not a surprise.  Parallelization by force-decomposition works
best when the number of processors is a square of an integer:  4, 9, 16,
25.... With only two processors, the expense of the communication costs
will not be offset by the speedup of the force loop.

Best regards,

  --Dan Gezelter

-- 
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   J. Daniel Gezelter
   Assistant Professor
   Department of Chemistry and Biochemistry
   251 Nieuwland Science Hall
   University of Notre Dame
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   phone:  +1 (574) 631-7595
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