./56_recipspace/getmpw.F90

ABINIT/getmpw

ABINIT/getmpw [ Functions ]

NAME

 getmpw

FUNCTION

 From input ecut, combined with ucvol and gmet, compute recommended mpw
 mpw is the maximum number of plane-waves in the wave-function basis
  for one processor of the WF group

 Copyright (C) 1998-2017 ABINIT group (DCA, XG, GMR)
 This file is distributed under the terms of the
 GNU General Public License, see ~abinit/COPYING
 or http://www.gnu.org/copyleft/gpl.txt .
 For the initials of contributors, see ~abinit/doc/developers/contributors.txt .

INPUTS

 ecut=plane-wave cutoff energy in Hartrees
 exchn2n3d=if n1, n2 and n3 are exchanged
 gmet(3,3)=reciprocal space metric (bohr**-2).
 istwfk(nkpt)=input option parameter that describes the storage of wfs
 kptns(3,nkpt)=real(dp) array for k points (normalisation is already taken into account)
 mpi_enreg=information about MPI parallelization
 nkpt=integer number of k points in the calculation

OUTPUT

 mpw=maximal number of plane waves over all k points of the processor
  (for one processor of the WF group)

PARENTS

      dfpt_looppert,memory_eval,mpi_setup,scfcv

CHILDREN

      kpgsph,wrtout

SOURCE

 39 #if defined HAVE_CONFIG_H
 40 #include "config.h"
 41 #endif
 42 
 43 #include "abi_common.h"
 44 
 45 subroutine getmpw(ecut,exchn2n3d,gmet,istwfk,kptns,mpi_enreg,mpw,nkpt)
 46 
 47  use defs_basis
 48  use defs_abitypes
 49  use m_profiling_abi
 50  use m_errors
 51 
 52  use m_fftcore, only : kpgsph
 53 
 54 !This section has been created automatically by the script Abilint (TD).
 55 !Do not modify the following lines by hand.
 56 #undef ABI_FUNC
 57 #define ABI_FUNC 'getmpw'
 58  use interfaces_14_hidewrite
 59 !End of the abilint section
 60 
 61  implicit none
 62 
 63 !Arguments ------------------------------------
 64 !scalars
 65  integer,intent(in) :: exchn2n3d,nkpt
 66  integer,intent(out) :: mpw
 67  real(dp),intent(in) :: ecut
 68  type(MPI_type),intent(inout) :: mpi_enreg
 69 !arrays
 70  integer,intent(in) :: istwfk(nkpt)
 71  real(dp),intent(in) :: gmet(3,3),kptns(3,nkpt)
 72 
 73 !Local variables-------------------------------
 74 !scalars
 75  integer :: ikpt,istwf_k,npw
 76 ! integer :: npwwrk,pad=50
 77 ! real(dp) :: scale=1.3_dp
 78  character(len=500) :: message
 79 !arrays
 80  integer,allocatable :: kg(:,:)
 81  real(dp) :: kpoint(3)
 82 
 83 ! *************************************************************************
 84 
 85 !An upper bound for mpw, might be obtained as follows
 86 !the average number of plane-waves in the cutoff sphere is
 87 !npwave = (2*ecut)**(3/2) * ucvol / (6*pi**2)
 88 !the upper bound is calculated as
 89 !npwwrk = int(scale * npwave) + pad
 90 !rescale so an upper bound
 91 !npwave=nint(ucvol*(2.0_dp*ecut)**1.5_dp/(6.0_dp*pi**2))
 92 !npwwrk=nint(dble(npwave)*scale)+pad
 93 
 94  ABI_ALLOCATE(kg,(3,100))
 95 
 96 !set mpw to zero, as needed for only counting in kpgsph
 97  mpw = 0
 98 
 99 !Might be parallelized over k points ? !
100  do ikpt = 1,nkpt
101 !  Do computation of G sphere, returning npw
102    kpoint(:)=kptns(:,ikpt)
103    istwf_k=istwfk(ikpt)
104    call kpgsph(ecut,exchn2n3d,gmet,0,ikpt,istwf_k,kg,kpoint,0,mpi_enreg,0,npw)
105    mpw = max(npw,mpw)
106  end do
107 
108  write(message,'(a,i0)') ' getmpw: optimal value of mpw= ',mpw
109  call wrtout(std_out,message,'COLL')
110 
111  ABI_DEALLOCATE(kg)
112 
113 end subroutine getmpw

TABLE OF CONTENTS

ABINIT/getmpw [ Functions ]