| 1 |
module long_range_forces |
| 2 |
use definitions, ONLY : dp, ndim |
| 3 |
use simulation |
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implicit none |
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|
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real(kind = dp ) :: rlistsq |
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real(kind = dp ) :: rcutsq |
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integer, allocatable, dimension(:) :: point |
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integer, allocatable, dimension(:) :: list |
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contains |
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|
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subroutine long_range_force ( check_exclude, & |
| 27 |
pair_i, pair_j, n_pairs, natoms, sigma, epslon, & |
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box, & |
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rx, ry, rz, fx, fy, fz, & |
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v, & |
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update, point, list, maxnab, & |
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rx0, ry0, rz0, & |
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ux, uy, uz, & |
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tx, ty, tz, & |
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ex, ey, ez, & |
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mu, rrf, rtaper, & |
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dielectric, & |
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is_dipole, is_vdw, is_lj, is_ssd, & |
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Axx, Axy, Axz, & |
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Ayx, Ayy, Ayz, & |
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Azx, Azy, Azz ) |
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|
| 43 |
implicit none |
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|
| 45 |
! This routine implements the Verlet neighbor list for all of |
| 46 |
! the long range force calculations. After a pair has been |
| 47 |
! determined to lie within the neighbor list, the pair is passed |
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! to the appropriate force functions. |
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! Passed Arguments |
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|
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integer :: n_pairs ! the number of excluded pairs |
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integer :: natoms ! the number of atoms in the system |
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integer :: maxnab ! the max number of neighbors for the verlet list |
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|
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logical(kind=2) :: check_exclude ! boolean to check for exclusion pairs |
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logical(kind=2) :: update ! boolean to update the neighbor list |
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|
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double precision rcut ! the VDW/LJ cutoff radius |
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double precision rlist ! Verlet list cutoff |
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double precision box_x, box_y, box_z ! periodic boundry conditions |
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double precision rrf ! dipole reaction field cutoff |
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double precision rtaper ! the taper radius of the rxn field |
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double precision dielectric ! the dielectric cnst. of the rxn field |
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double precision v ! the potential energy |
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! Passed Arrays |
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|
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integer, dimension(n_pairs):: pair_i, pair_j ! the excluded pairs i and j |
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integer, dimension(natoms) :: point ! the Verlet list ptr array |
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integer, dimension(maxnab) :: list ! the verlet list |
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|
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logical(kind=2), dimension(natoms) :: is_dipole ! dipole boolean array |
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logical(kind=2), dimension(natoms) :: is_vdw ! VDW boolean array |
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logical(kind=2), dimension(natoms) :: is_lj ! LJ boolean array |
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logical(kind=2), dimension(natoms) :: is_ssd ! ssd boolean array |
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|
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double precision, dimension(natoms) :: sigma ! VDW/LJ distance prmtr. |
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double precision, dimension(natoms) :: epslon ! VDW/LJ well depth prmtr. |
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double precision, dimension(natoms) :: rx, ry, rz ! positions |
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double precision, dimension(natoms) :: fx, fy, fz ! forces |
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double precision, dimension(natoms) :: rx0, ry0, rz0 ! intial verlet positions |
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double precision, dimension(natoms) :: ux, uy, uz ! dipole unit vectors |
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double precision, dimension(natoms) :: tx, ty, tz ! torsions |
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double precision, dimension(natoms) :: ex, ey, ez ! reacion field |
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double precision, dimension(natoms) :: mu ! dipole moments |
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double precision, dimension(natoms) :: Axx, Axy, Axz ! rotational array |
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double precision, dimension(natoms) :: Ayx, Ayy, Ayz ! |
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double precision, dimension(natoms) :: Azx, Azy, Azz ! |
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|
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! local variables |
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|
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double precision rxi, ryi, rzi |
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double precision rcutsq, rlstsq, rrfsq, rijsq, rij |
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double precision rxij, ryij, rzij |
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double precision prerf ! a reaction field preterm |
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|
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double precision, dimension(9,natoms) :: A |
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|
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integer :: i, j, k, ix, jx, nlist |
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integer :: jbeg, jend, jnab |
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logical :: exclude_temp1, exclude_temp2, exclude |
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!******************************************************************* |
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|
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do i=1, natoms |
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A(1,i) = Axx(i) |
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A(2,i) = Axy(i) |
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A(3,i) = Axz(i) |
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|
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A(4,i) = Ayx(i) |
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A(5,i) = Ayy(i) |
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A(6,i) = Ayz(i) |
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A(7,i) = Azx(i) |
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A(8,i) = Azy(i) |
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A(9,i) = Azz(i) |
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end do |
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|
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rlstsq = rlist * rlist |
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rcutsq = rcut * rcut |
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rrfsq = rrf * rrf |
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|
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prerf = 14.39257d0 * 2.0d0 * ( dielectric - 1.0d0 ) / & |
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( ( 2.0d0 * dielectric + 1.0d0 ) * rrfsq * rrf ) |
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|
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! ** zero forces ** |
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do I = 1, natoms |
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fx(i) = 0.0d0 |
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fy(i) = 0.0d0 |
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fz(i) = 0.0d0 |
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tx(i) = 0.0d0 |
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ty(i) = 0.0d0 |
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tz(i) = 0.0d0 |
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ex(i) = 0.0d0 |
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ey(i) = 0.0d0 |
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ez(i) = 0.0d0 |
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end do |
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V = 0.0d0 |
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|
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if ( update ) then |
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! ** save current configuration, construct ** |
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! ** neighbour list and calculate forces ** |
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call long_range_save(natoms,rx,ry,rz,rx0,ry0,rz0) |
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|
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nlist = 0 |
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do i = 1, natoms - 1 |
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point(i) = nlist + 1 |
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rxi = rx(i) |
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ryi = ry(i) |
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rzi = rz(i) |
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do j = i + 1, natoms |
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rxij = rx(j) - rxi |
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ryij = ry(j) - ryi |
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rzij = rz(j) - rzi |
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|
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exclude = .false. |
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if( check_exclude ) then |
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do k = 1, n_pairs |
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! add 1 for c -> fortran indexing |
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ix = pair_i(k) + 1 |
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jx = pair_j(k) + 1 |
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exclude_temp1 = (i.eq.ix).and.(j.eq.jx) |
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exclude_temp2 = (i.eq.jx).and.(j.eq.ix) |
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|
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if(exclude_temp1.or.exclude_temp2) then |
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|
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exclude = .true. |
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endif |
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enddo |
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endif |
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|
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if(.not.exclude) then |
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|
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rxij = rxij - box_x * dsign( 1.0d0, rxij ) & |
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* int( (dabs( rxij / box_x ) + 0.5d0) ) |
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ryij = ryij - box_y * dsign( 1.0d0, ryij ) & |
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* int( (dabs( ryij / box_y ) + 0.5d0) ) |
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rzij = rzij - box_z * dsign( 1.0d0, rzij ) & |
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* int( (dabs( rzij / box_z ) + 0.5d0) ) |
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|
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rijsq = rxij * rxij + ryij * ryij + rzij * rzij |
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if ( rijsq .lt. rlstsq ) then |
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nlist = nlist + 1 |
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list(nlist) = j |
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! ** remove this check if maxnab is appropriate ** |
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|
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if ( nlist .eq. maxnab ) then |
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write(*,*) i, j, nlist, maxnab, rijsq, rlstsq |
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stop 'list too small' |
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endif |
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|
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if ( rijsq .lt. rcutsq ) then |
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|
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if ( is_vdw(i) .and. is_vdw(j) ) then |
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call force_VDW( i, j, rcutsq, rijsq, sigma, epslon, & |
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v, fx, fy, fz, rxij, ryij, rzij, natoms ) |
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endif |
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|
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if ( is_lj(i) .and. is_lj(j) ) then |
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call force_lj( i, j, rcutsq, rijsq, sigma, epslon, v, & |
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fx, fy, fz, rxij, ryij, rzij, natoms ) |
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endif |
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|
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if( is_ssd(i) .and. is_ssd(j) ) then |
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|
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rij = dsqrt(rijsq); |
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|
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call ssd_forces( natoms, i, j, i, j, rxij, ryij, rzij, & |
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rij, v, rijsq, fx, fy, fz, tx, ty, tz, A ) |
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end if |
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|
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endif |
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|
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if( is_dipole(i) .and. is_dipole(j) ) then |
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if( rijsq .lt. rrfsq ) then |
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|
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call dipole_rf( i, j, rrfsq, rijsq, v, rxij, ryij, & |
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rzij, rrf, dielectric, rtaper, natoms, & |
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ux, uy, uz, mu, fx, fy, fz, tx, ty, tz, & |
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ex, ey, ez, prerf ) |
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endif |
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end if |
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endif |
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endif |
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|
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enddo |
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|
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end do |
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|
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point(natoms) = nlist + 1 |
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|
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else |
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|
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|
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!** use the list to find the neighbours ** |
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|
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do i = 1, natoms - 1 |
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|
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jbeg = point(i) |
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jend = point(i+1) - 1 |
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|
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!** check that atom i has neighbours ** |
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|
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if( jbeg .le. jend ) then |
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|
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rxi = rx(i) |
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ryi = ry(i) |
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rzi = rz(i) |
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|
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do jnab = jbeg, jend |
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|
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j = list(jnab) |
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|
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rxij = rx(j) - rxi |
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ryij = ry(j) - ryi |
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rzij = rz(j) - rzi |
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|
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rxij = rxij - box_x * dsign( 1.0d0, rxij ) & |
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* int( dabs( rxij / box_x ) + 0.5d0 ) |
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ryij = ryij - box_y * dsign( 1.0d0, ryij ) & |
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* int( dabs( ryij / box_y ) + 0.5d0 ) |
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rzij = rzij - box_z * dsign( 1.0d0, rzij ) & |
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* int( dabs( rzij / box_z ) + 0.5d0 ) |
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|
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rijsq = rxij * rxij + ryij * ryij + rzij * rzij |
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|
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if ( rijsq .lt. rcutsq ) then |
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|
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if ( is_vdw(i) .and. is_vdw(j) ) then |
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call force_VDW( i, j, rcutsq, rijsq, sigma, epslon, & |
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v, fx, fy, fz, rxij, ryij, rzij, natoms ) |
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endif |
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|
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if ( is_lj(i) .and. is_lj(j) ) then |
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call force_lj( i, j, rcutsq, rijsq, sigma, epslon, v, & |
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fx, fy, fz, rxij, ryij, rzij, natoms ) |
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endif |
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|
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if( is_ssd(i) .and. is_ssd(j) ) then |
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|
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rij = dsqrt(rijsq); |
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|
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call ssd_forces( natoms, i, j, i, j, rxij, ryij, rzij, & |
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rij, v, rijsq, fx, fy, fz, tx, ty, tz, A ) |
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end if |
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|
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endif |
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|
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|
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if( is_dipole(i) .and. is_dipole(j) ) then |
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if( rijsq .lt. rrfsq ) then |
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|
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call dipole_rf( i, j, rrfsq, rijsq, v, rxij, ryij, & |
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rzij, rrf, dielectric, rtaper, natoms, & |
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ux, uy, uz, mu, fx, fy, fz, tx, ty, tz, & |
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ex, ey, ez, prerf ) |
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endif |
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endif |
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|
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end do |
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endif |
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end do |
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endif |
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|
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! calculate the reaction field effect |
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|
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!!$ call reaction_field( v, prerf, natoms, mu, ux, uy, uz, tx, ty, tz, & |
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!!$ ex, ey, ez, is_dipole ) |
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|
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|
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end subroutine long_range_force |
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|
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|
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|
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subroutine long_range_check ( rcut, rlist, update, natoms, & |
| 344 |
rx,ry,rz,rx0,ry0,rz0) |
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|
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|
| 347 |
!******************************************************************* |
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!** decides whether the list needs to be reconstructed. ** |
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!** ** |
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!** principal variables: ** |
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!** ** |
| 352 |
!** real rx(n),ry(n),rz(n) atom positions ** |
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!** real rx0(n),ry0(n),rz0(n) coordinates at last update ** |
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!** real rlist radius of verlet list ** |
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!** real rcut cutoff distance for forces ** |
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!** real dispmx largest displacement ** |
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!** integer n number of atoms ** |
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!** logical update if true the list is updated ** |
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!** ** |
| 360 |
!** usage: ** |
| 361 |
!** ** |
| 362 |
!** check is called to set update before every call to force. ** |
| 363 |
!******************************************************************* |
| 364 |
|
| 365 |
|
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! Passed variables |
| 367 |
|
| 368 |
integer :: natoms |
| 369 |
|
| 370 |
logical(kind=2) :: update |
| 371 |
|
| 372 |
double precision rcut, rlist |
| 373 |
|
| 374 |
! Passed arrays |
| 375 |
double precision, dimension(natoms) :: rx, ry, rz |
| 376 |
double precision, dimension(natoms) :: rx0, ry0, rz0 |
| 377 |
|
| 378 |
! local variables |
| 379 |
|
| 380 |
double precision dispmx |
| 381 |
|
| 382 |
integer :: i |
| 383 |
|
| 384 |
!******************************************************************* |
| 385 |
|
| 386 |
!** calculate maximum displacement since last update ** |
| 387 |
|
| 388 |
dispmx = 0.0d0 |
| 389 |
|
| 390 |
do i = 1, natoms |
| 391 |
|
| 392 |
!write(*,*) 'calling displacement', i |
| 393 |
|
| 394 |
dispmx = max ( dabs ( rx(i) - rx0(i) ), dispmx ) |
| 395 |
dispmx = max ( dabs ( ry(i) - ry0(i) ), dispmx ) |
| 396 |
dispmx = max ( dabs ( rz(i) - rz0(i) ), dispmx ) |
| 397 |
|
| 398 |
!write(*,*) 'called displacement', i |
| 399 |
|
| 400 |
end do |
| 401 |
|
| 402 |
!** a conservative test of the list skin crossing ** |
| 403 |
|
| 404 |
dispmx = 2.0d0 * dsqrt ( 3.0d0 * dispmx ** 2 ) |
| 405 |
|
| 406 |
update = ( dispmx .gt. ( rlist - rcut ) ) |
| 407 |
|
| 408 |
|
| 409 |
return |
| 410 |
end subroutine long_range_check |
| 411 |
|
| 412 |
|
| 413 |
|
| 414 |
subroutine long_range_save(natoms,rx,ry,rz,rx0,ry0,rz0) |
| 415 |
|
| 416 |
|
| 417 |
!******************************************************************* |
| 418 |
!** saves current configuration for future checking. ** |
| 419 |
!** ** |
| 420 |
!** principal variables: ** |
| 421 |
!** ** |
| 422 |
!** real rx(n),ry(n),rz(n) atom positions ** |
| 423 |
!** real rx0(n),ry0(n),rz0(n) storage locations for save ** |
| 424 |
!** integer n number of atoms ** |
| 425 |
!** ** |
| 426 |
!** usage: ** |
| 427 |
!** ** |
| 428 |
!** save is called whenever the new verlet list is constructed. ** |
| 429 |
!******************************************************************* |
| 430 |
|
| 431 |
integer :: i |
| 432 |
|
| 433 |
integer :: natoms |
| 434 |
|
| 435 |
double precision, dimension(natoms) :: rx, ry, rz |
| 436 |
double precision, dimension(natoms) :: rx0, ry0, rz0 |
| 437 |
|
| 438 |
!******************************************************************* |
| 439 |
|
| 440 |
do i = 1, natoms |
| 441 |
|
| 442 |
rx0(i) = rx(i) |
| 443 |
ry0(i) = ry(i) |
| 444 |
rz0(i) = rz(i) |
| 445 |
|
| 446 |
end do |
| 447 |
|
| 448 |
return |
| 449 |
end subroutine long_range_save |
| 450 |
|
| 451 |
end module long_range_forces |
