mirror of https://gitlab.com/QEF/q-e.git
61 lines
1.5 KiB
Fortran
61 lines
1.5 KiB
Fortran
!
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! Copyright (C) 2001 PWSCF group
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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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!
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!-----------------------------------------------------------------------
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subroutine g_psi (lda, n, m, psi, e)
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!-----------------------------------------------------------------------
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!
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! This routine computes an estimate of the inverse Hamiltonian
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! and applies it to m wavefunctions
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!
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! first the input variables
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!
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use parameters
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use g_psi_mod
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implicit none
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integer :: lda, n, m
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! input: the leading dimension of psi
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! input: the real dimension of psi
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! input: the number of bands
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real(kind=DP) :: e (m)
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! input: the eigenvectors
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complex(kind=DP) :: psi (lda, m)
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! inp/out: the psi vector
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!
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! One parameter
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!
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real(kind=DP) :: eps
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! a small number
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parameter (eps = 1.0d-4)
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!
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! The local variables
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!
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real(kind=DP) :: denm ! the denominator
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integer :: k, i
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! counter on psi functions
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! counter on G vectors
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call start_clock ('g_psi')
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do k = 1, m
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do i = 1, n
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denm = h_diag (i) - e (k) * s_diag (i)
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!
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! denm = g2+v(g=0) - e(k)
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!
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if (abs (denm) .lt.eps) denm = sign (eps, denm)
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!
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! denm = sign( max( abs(denm),eps ), denm )
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!
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psi (i, k) = psi (i, k) / denm
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enddo
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enddo
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call stop_clock ('g_psi')
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return
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end subroutine g_psi
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