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Check on symmetry group extended to fractional translations - temporary fix 

for a rather unpleasant situation: Si with origin in the middle of the bond
doesn't work any longer!


git-svn-id: http://qeforge.qe-forge.org/svn/q-e/trunk/espresso@6316 c92efa57-630b-4861-b058-cf58834340f0
This commit is contained in:
giannozz 2010-01-25 11:17:39 +00:00
parent 8e4d62d070
commit 67da7be0d1
1 changed files with 14 additions and 6 deletions
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20
PW/sgama.f90
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@ -58,7 +58,7 @@ SUBROUTINE sgama ( nrot, nat, s, sname, t_rev, at, bg, tau, ityp, &
!
nsym = copy_sym ( nrot, sym, s, sname, ftau, nat, irt, t_rev )
!
IF ( .not. is_group(nsym,s) ) THEN
IF ( .not. is_group(nsym,s,nr1,nr2,nr3,ftau) ) THEN
CALL infomsg ('sgama', 'Not a group! symmetry disabled')
nsym = 1
END IF
@ -121,30 +121,38 @@ END FUNCTION copy_sym
!
!-----------------------------------------------------------------------
LOGICAL FUNCTION is_group (nsym, s)
LOGICAL FUNCTION is_group (nsym, s, nr1, nr2, nr3, ftau)
!-----------------------------------------------------------------------
!
! Checks that {S} is a group
!
IMPLICIT NONE
!
INTEGER, INTENT(IN) :: nsym, s(3,3,nsym)
INTEGER, INTENT(IN) :: nsym, s(3,3,nsym), ftau(3,nsym), nr1,nr2,nr3
! nsym = number of symmetry operations
! s = rotation matrix (in crystal axis, represented by integers)
! ftau = fraftionary translations (in crystal axis, multiplied by nr*)
!
INTEGER :: isym, jsym, ksym, ss (3, 3)
INTEGER :: isym, jsym, ksym, ss (3, 3), stau(3)
LOGICAL :: found, smn
!
DO isym = 1, nsym
DO jsym = 1, nsym
!
ss = MATMUL (s(:,:,jsym),s(:,:,isym))
stau(:)= ftau(:,jsym) + s(1,:,jsym)*ftau(1,isym) + &
s(2,:,jsym)*ftau(2,isym) + s(3,:,jsym)*ftau(3,isym)
!
! here we check that the input matrices really form a group
! here we check that the input matrices really form a group:
! S(k) = S(j)*S(i)
! ftau_k = S(j)*ftau_i modulo a lattice vector
!
found = .false.
DO ksym = 1, nsym
smn = ALL ( s(:,:,ksym) == ss(:,:) )
smn = ALL( s(:,:,ksym) == ss(:,:) ) .AND. &
( MOD( ftau(1,ksym)-stau(1), nr1 ) == 0 ) .AND. &
( MOD( ftau(2,ksym)-stau(2), nr2 ) == 0 ) .AND. &
( MOD( ftau(3,ksym)-stau(3), nr3 ) == 0 )
IF (smn) THEN
IF (found) THEN
is_group = .false.