[Pw_forum] Too many r-vectors?

Paolo Giannozzi paolo.giannozzi at uniud.it
Mon Mar 10 16:49:52 CET 2014

There is a parameter "mxr" set to 50 in a few routines:
   espresso/PW/src/ewald_dipole.f90:  integer, parameter :: mxr = 50
   espresso/PW/src/ewald.f90:  integer, parameter :: mxr = 50
   espresso/PW/src/force_ew.f90:  integer, parameter :: mxr=50
   espresso/PW/src/stres_ewa.f90:  integer, parameter :: mxr = 50
This is maximum number of neighboring cell used in Ewald sums in
real space. Since very few such vectors are usually needed in order
to have converged Ewald sums, 50 is usually more than sufficient.
Try to increase it to 100 or so, recompile.


On Mon, 2014-03-10 at 13:59 +0000, Harper, Lenora K. wrote:
> Dear Sir or Madam,
> I am running a vc-relax calculation on an organic 78 atom molecular
> system under extreme pressure (50 kbar) and am receiving an error,
> "too many r-vectors." I see that my problem could lie in the fact that
> my cutoffs are too low. Which cutoff are we speaking of and what would
> be an acceptable cutoff for this type of system?
> Thank you for your time,
> Lenora Harper
> Old Dominion University
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 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222 

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