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45 lines
996 B
Fortran
45 lines
996 B
Fortran
subroutine gga_exchange_energy(DFA,nEns,wEns,nGrid,weight,rho,drho,Ex)
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! Select GGA exchange functional for energy calculation
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implicit none
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include 'parameters.h'
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! Input variables
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character(len=12),intent(in) :: DFA
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integer,intent(in) :: nEns
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double precision,intent(in) :: wEns(nEns)
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integer,intent(in) :: nGrid
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double precision,intent(in) :: weight(nGrid)
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double precision,intent(in) :: rho(nGrid)
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double precision,intent(in) :: drho(3,nGrid)
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! Output variables
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double precision :: Ex
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select case (DFA)
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! Gill's 96 exchange functional
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case ('G96')
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call G96_gga_exchange_energy(DFA,nEns,wEns,nGrid,weight,rho,drho,Ex)
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! Becke's 88 exchange functional
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case ('B88')
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call B88_gga_exchange_energy(DFA,nEns,wEns,nGrid,weight,rho,drho,Ex)
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case default
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call print_warning('!!! GGA exchange functional not available !!!')
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stop
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end select
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end subroutine gga_exchange_energy
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