[Pw_forum] Too many r-vectors?

[pourya]

professor Paolo Giannozzi and Dear L.Harper-san

Hi,

I appreciate for professor Paolo Giannozzi answer and Dear L.Harper-san 
for your question. I have same problem when I wanted to calculated 
twisted bilayer graphene there is 76 atoms is one unit cell. I just 
would like to know that after changing these value I have to compile 
just pw again or whole package.

Best Regard,

Pourya Ayria
PhD student
Tohoku University Japan
On 03/11/2014 12:49 AM, Paolo Giannozzi wrote:
> 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.
>
> P.
>
> 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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