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ABINIT/remove_inversion [ Functions ]

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NAME

 remove_inversion

FUNCTION

  Remove the inversion symmetry from a symmetry set as well
  all the improper rotations (if present)

COPYRIGHT

  Copyright (C) 2008-2018 ABINIT group (MG)
  This file is distributed under the terms of the
  GNU General Public License, see ~abinit/COPYING
  or http://www.gnu.org/copyleft/gpl.txt .

INPUTS

  nsym=initial number of symmetries
  symrel(3,3,nsym)=Initial set of symmetry operarations in real space
  tnons(3,nsym)=Initial fractional translations

OUTPUT

  nsym_out=Number of symmetries in the set without improper rotation
  symrel_out(:,:) [pointer] = output symmetries without improper rotations
  tnons_out(:) [pointer] = fractional translations associated to symrel_out
  pinv=-1 if the inversion has been removed, 1 otherwise

NOTES

  Note the use of pointers, memory is allocated inside the procedure and passed back
  to the caller. Thus memory deallocation is relegated to the caller. To be on the safe side
  the pointers should be nullified before entering.

PARENTS

      m_crystal,m_io_kss,outkss

CHILDREN

      set2unit,symdet,wrtout

SOURCE

 40 #if defined HAVE_CONFIG_H
 41 #include "config.h"
 42 #endif
 43 
 44 #include "abi_common.h"
 45 
 46 subroutine remove_inversion(nsym,symrel,tnons,nsym_out,symrel_out,tnons_out,pinv)
 47 
 48  use defs_basis
 49  use m_profiling_abi
 50  use m_errors
 51 
 52  use m_numeric_tools, only : isinteger, set2unit
 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 'remove_inversion'
 58  use interfaces_14_hidewrite
 59  use interfaces_41_geometry, except_this_one => remove_inversion
 60 !End of the abilint section
 61 
 62  implicit none
 63 
 64 !Arguments ------------------------------------
 65 !scalars
 66  integer,intent(in) :: nsym
 67  integer,intent(out) :: nsym_out,pinv
 68 !arrays
 69  integer,intent(in) :: symrel(3,3,nsym)
 70  integer,pointer :: symrel_out(:,:,:)
 71  real(dp),intent(in) :: tnons(3,nsym)
 72  real(dp),pointer :: tnons_out(:,:)
 73 
 74 !Local variables-------------------------------
 75 !scalars
 76  integer :: is,is2,is_discarded,is_inv,is_retained,nsym2
 77  logical :: found
 78  character(len=500) :: msg
 79 !arrays
 80  integer :: determinant(nsym),inversion(3,3),symrel2(3,3,nsym)
 81  real(dp) :: dtnons(3),tnons2(3,nsym)
 82 
 83 ! *********************************************************************
 84 
 85  msg = 'Removing inversion related symmetrie from initial set'
 86  MSG_WARNING(msg)
 87 !
 88 !=== Find the occurence of the inversion symmetry ===
 89  call set2unit(inversion) ; inversion=-inversion
 90 
 91  is_inv=0 ; found=.FALSE.
 92  do while (is_inv<nsym .and. .not.found)
 93    is_inv=is_inv+1 ; found=ALL(symrel(:,:,is_inv)==inversion)
 94  end do
 95  if (found) then
 96    write(msg,'(a,i3)')' The inversion is symmetry operation no. ',is_inv
 97  else
 98    write(msg,'(a)')' The inversion was not found in the symmetries list.'
 99  end if
100  call wrtout(std_out,msg,'COLL')
101 !
102 !=== Find the symmetries that are related through the inversion symmetry ===
103  call symdet(determinant,nsym,symrel)
104  nsym2=0
105  do is=1,nsym-1
106    do is2=is+1,nsym
107 
108      dtnons(:)=tnons(:,is2)-tnons(:,is)-tnons(:,is_inv)
109      found=ALL(symrel(:,:,is)==-symrel(:,:,is2)).and.isinteger(dtnons,tol8)
110 
111      if (found) then
112        nsym2=nsym2+1
113 !      * Retain symmetries with positive determinant
114        if (ALL(tnons(:,is2)<tol8).and.ALL(tnons(:,is)<tol8)) then
115          is_retained=is2 ; is_discarded=is
116          if (determinant(is)==1) then
117            is_retained=is  ; is_discarded=is2
118          end if
119        else if (ALL(tnons(:,is2)<tol8)) then
120          is_retained=is2 ; is_discarded=is
121        else
122          is_retained=is ;  is_discarded=is2
123        end if
124 
125        symrel2(:,:,nsym2)=symrel(:,:,is_retained)
126        tnons2   (:,nsym2)=tnons   (:,is_retained)
127        write(msg,'(a,i3,a,i3,3a,i3,a)')&
128 &       ' Symmetry operations no. ',is,' and no. ',is2,&
129 &       ' are related through the inversion.',ch10,&
130 &       ' Symmetry operation no. ',is_discarded,' will be suppressed.'
131        call wrtout(std_out,msg,'COLL')
132      end if ! found
133 
134    end do !is2
135  end do !is
136 
137  if (nsym2/=(nsym/2).or.nsym==1) then
138    write(msg,'(a)')' Program uses the original set of symmetries '
139    call wrtout(std_out,msg,'COLL')
140    nsym_out=nsym
141    ABI_ALLOCATE(symrel_out,(3,3,nsym))
142    ABI_ALLOCATE(tnons_out,(3,nsym))
143    symrel_out(:,:,:)=symrel(:,:,1:nsym)
144    tnons_out(:,:)=tnons(:,1:nsym)
145    pinv=1
146  else
147    write(msg,'(a)')' Inversion related operations have been suppressed from symmetries list.'
148    call wrtout(std_out,msg,'COLL')
149    nsym_out=nsym2
150    ABI_ALLOCATE(symrel_out,(3,3,nsym2))
151    ABI_ALLOCATE(tnons_out,(3,nsym2))
152    symrel_out(:,:,:)=symrel2(:,:,1:nsym2)
153    tnons_out(:,:)=tnons(:,1:nsym2)
154    pinv=-1
155  end if
156 
157 end subroutine remove_inversion