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ABINIT/irreducible_set_pert [ Functions ]

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NAME

 irreducible_set_pert

FUNCTION

 Determines a set of perturbations that form a basis
 in that, using symmetry, they can be used to generate
 all other perturbations that are asked to be calculated (target).

COPYRIGHT

 Copyright (C) 1999-2018 ABINIT group (XG)
 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

  indsym(4,nsym,natom)=indirect indexing array described above: for each
   isym,iatom, fourth element is label of atom into which iatom is sent by
   INVERSE of symmetry operation isym; first three elements are the primitive
   translations which must be subtracted after the transformation to get back
   to the original unit cell.
  mpert =maximum number of iper
  natom= number of atoms
  nsym=number of space group symmetries
  rfdir(3)=direction for the perturbations
  rfpert(mpert)=information on the perturbations
  symrec(3,3,nsym)=3x3 matrices of the group symmetries (reciprocal space)
  symrel(3,3,nsym)=3x3 matrices of the group symmetries (real space)
  symq(4,2,nsym)= (integer) three first numbers define the G vector;
   fourth number is 0 if the q-vector is not preserved, is 1 otherwise
   second index is one without time-reversal symmetry, two with time-reversal symmetry

OUTPUT

   pertsy(3,mpert)= the target perturbation is described by the two last indices (idir, and ipert),
                    the value is 0, 1 or -1, see notes.

NOTES

 Output will be in the pertsy array,
   0 for non-target perturbations
   1 for basis perturbations
  -1 for perturbations that can be found from basis perturbations

PARENTS

      get_npert_rbz,m_dvdb,respfn

CHILDREN

SOURCE

 53 #if defined HAVE_CONFIG_H
 54 #include "config.h"
 55 #endif
 56 
 57 #include "abi_common.h"
 58 
 59 
 60 subroutine irreducible_set_pert(indsym,mpert,natom,nsym,pertsy,rfdir,rfpert,symq,symrec,symrel)
 61 
 62  use defs_basis
 63  use m_profiling_abi
 64 
 65 !This section has been created automatically by the script Abilint (TD).
 66 !Do not modify the following lines by hand.
 67 #undef ABI_FUNC
 68 #define ABI_FUNC 'irreducible_set_pert'
 69 !End of the abilint section
 70 
 71  implicit none
 72 
 73 !Arguments -------------------------------
 74 !scalars
 75  integer,intent(in) :: mpert,natom,nsym
 76 !arrays
 77  integer,intent(in) :: indsym(4,nsym,natom),rfdir(3),rfpert(mpert)
 78  integer,intent(in) :: symq(4,2,nsym),symrec(3,3,nsym),symrel(3,3,nsym)
 79  integer,intent(out) :: pertsy(3,mpert)
 80 
 81 !Local variables -------------------------
 82 !scalars
 83  integer :: found,idir1,idisy1,ii,ipert1,ipesy1,isign,isym,itirev,jj
 84 !arrays
 85  integer :: sym1(3,3)
 86 
 87 ! *********************************************************************
 88 
 89 !Zero pertsy
 90  pertsy(:,:)=0
 91 
 92  do ipert1=1,mpert
 93    do idir1=1,3
 94      if(rfpert(ipert1)==1.and.rfdir(idir1)==1)then
 95 !      write(std_out,*)' for candidate idir =',idir1,' ipert = ',ipert1
 96 
 97 !      Loop on all symmetries, including time-reversal
 98        do isym=1,nsym
 99          do itirev=1,2
100            isign=3-2*itirev
101 
102            if(symq(4,itirev,isym)/=0)then
103 
104              found=1
105 
106 !            Here select the symmetric of ipert1
107              if(ipert1<=natom)then
108                ipesy1=indsym(4,isym,ipert1)
109                do ii=1,3
110                  do jj=1,3
111                    sym1(ii,jj)=symrec(ii,jj,isym)
112                  end do
113                end do
114              else if(ipert1==(natom+2) .or. ipert1==(natom+6))then
115                ipesy1=ipert1
116                do ii=1,3
117                  do jj=1,3
118                    sym1(ii,jj)=symrel(ii,jj,isym)
119                  end do
120                end do
121              else
122                found=0
123              end if
124 
125 !            Now that a symmetric perturbation has been obtained,
126 !            including the expression of the symmetry matrix, see
127 !            if the symmetric perturbations are available
128              if( found==1 ) then
129 
130                do idisy1=1,3
131                  if(sym1(idir1,idisy1)/=0)then
132                    if(pertsy(idisy1,ipesy1)==0)then
133                      found=0
134                      exit
135                    end if
136                  end if
137                end do
138              end if
139 
140 !            Now, if still found, then it is a symmetric
141 !            of some linear combination of existing perturbations
142              if(found==1)then
143 
144 !              DEBUG
145 !              write(std_out,*)' all found !  isym, isign= ',isym,isign
146 !              write(std_out,1010)((sym1(ii,jj),ii=1,3),jj=1,3)
147 !              write(std_out,1010)((sym2(ii,jj),ii=1,3),jj=1,3)
148 !              write(std_out,*)sumr,sumi
149 !              1010    format(9i4)
150 !              ENDDEBUG
151 
152                pertsy(idir1,ipert1)=-1
153                exit ! Exit loop on symmetry operations
154 
155              end if
156 
157            end if !  End loop on all symmetries + time-reversal
158          end do
159        end do
160 
161 !      Now that all symmetries have been examined,
162 !      if still not symmetric of a linear combination
163 !      of basis perturbations, then it is a basis perturbation
164        if(pertsy(idir1,ipert1)/=-1) pertsy(idir1,ipert1)=1
165 !      write(std_out,'(a,3i5)' ) ' irreducible_set_pert :',idir1,ipert1,pertsy(idir1,ipert1)
166 
167      end if ! End big loop on all elements
168    end do
169  end do
170 
171 end subroutine irreducible_set_pert