mirror of https://gitlab.com/QEF/q-e.git
43 lines
1.1 KiB
Fortran
43 lines
1.1 KiB
Fortran
!
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! Copyright (C) 2003 A. Smogunov
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! This file is distributed under the terms of the
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! GNU General Public License. See the file `License'
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! in the root directory of the present distribution,
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! or http://www.gnu.org/copyleft/gpl.txt .
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!
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subroutine kbloch(ntot, val)
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!
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! It obtaines complex k in 1st B.Z. for Bloch states from
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! lambda=\exp{ikd}, d is the unit cell length.
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! The result is in the units (2\pi/d)
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!
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#include "f_defs.h"
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USE kinds, only : DP
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use constants, only : tpi
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implicit none
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integer :: &
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ntot, & ! number of Bloch states
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in
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real(DP) :: rho, g1, g2, k1, k2
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complex(DP) :: &
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val(ntot) ! complex k values
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do in=1, ntot
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g1= DBLE(val(in))
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g2=AIMAG(val(in))
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rho=DSQRT(g1**2+g2**2)
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k1=DACOS(g1/rho)
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k2=-DLOG(rho)
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if (g2.le.0.d0) k1=tpi-k1
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k1=k1/tpi
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k2=k2/tpi
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k1=k1-1.d0*INT(k1)
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if (k1.gt.0.5d0) k1=k1-1.d0
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val(in)=CMPLX(k1,k2)
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! WRITE( stdout,'(i5, 2f12.7)') in, DBLE(val(in)), AIMAG(val(in))
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enddo
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return
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end subroutine kbloch
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