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Comparing trunk/OOPSE/libmdtools/calc_sticky_pair.F90 (file contents):
Revision 483 by gezelter, Wed Apr 9 04:06:43 2003 UTC vs.
Revision 727 by tim, Wed Aug 27 16:16:01 2003 UTC

# Line 9 | Line 9
9   !! @author Matthew Meineke
10   !! @author Christopher Fennel
11   !! @author J. Daniel Gezelter
12 < !! @version $Id: calc_sticky_pair.F90,v 1.8 2003-04-09 04:06:43 gezelter Exp $, $Date: 2003-04-09 04:06:43 $, $Name: not supported by cvs2svn $, $Revision: 1.8 $
12 > !! @version $Id: calc_sticky_pair.F90,v 1.13 2003-08-27 16:16:01 tim Exp $, $Date: 2003-08-27 16:16:01 $, $Name: not supported by cvs2svn $, $Revision: 1.13 $
13  
14   module sticky_pair
15  
# Line 27 | Line 27 | module sticky_pair
27    logical, save :: sticky_initialized = .false.
28    real( kind = dp ), save :: SSD_w0 = 0.0_dp
29    real( kind = dp ), save :: SSD_v0 = 0.0_dp
30 +  real( kind = dp ), save :: SSD_v0p = 0.0_dp
31    real( kind = dp ), save :: SSD_rl = 0.0_dp
32    real( kind = dp ), save :: SSD_ru = 0.0_dp
33 +  real( kind = dp ), save :: SSD_rlp = 0.0_dp
34    real( kind = dp ), save :: SSD_rup = 0.0_dp
35 +  real( kind = dp ), save :: SSD_rbig = 0.0_dp
36  
37    public :: check_sticky_FF
38    public :: set_sticky_params
# Line 44 | Line 47 | contains
47      return
48    end subroutine check_sticky_FF
49  
50 <  subroutine set_sticky_params(sticky_w0, sticky_v0)
51 <    real( kind = dp ), intent(in) :: sticky_w0, sticky_v0
50 >  subroutine set_sticky_params(sticky_w0, sticky_v0, sticky_v0p, &
51 >       sticky_rl, sticky_ru, sticky_rlp, sticky_rup)
52 >
53 >    real( kind = dp ), intent(in) :: sticky_w0, sticky_v0, sticky_v0p
54 >    real( kind = dp ), intent(in) :: sticky_rl, sticky_ru
55 >    real( kind = dp ), intent(in) :: sticky_rlp, sticky_rup
56      
57      ! we could pass all 5 parameters if we felt like it...
58      
59      SSD_w0 = sticky_w0
60      SSD_v0 = sticky_v0
61 <    SSD_rl = 2.75_DP
62 <    SSD_ru = 3.35_DP
63 <    SSD_rup = 4.0_DP
61 >    SSD_v0p = sticky_v0p
62 >    SSD_rl = sticky_rl
63 >    SSD_ru = sticky_ru
64 >    SSD_rlp = sticky_rlp
65 >    SSD_rup = sticky_rup
66 >
67 >    if (SSD_ru .gt. SSD_rup) then
68 >       SSD_rbig = SSD_ru
69 >    else
70 >       SSD_rbig = SSD_rup
71 >    endif
72    
73      sticky_initialized = .true.
74      return
# Line 61 | Line 76 | contains
76  
77    subroutine do_sticky_pair(atom1, atom2, d, rij, r2, A, pot, f, t, &
78         do_pot, do_stress)
79 <    
79 >
80      !! This routine does only the sticky portion of the SSD potential
81      !! [Chandra and Ichiye, J. Chem. Phys. 111, 2701 (1999)].
82      !! The Lennard-Jones and dipolar interaction must be handled separately.
83 <    
83 >
84      !! We assume that the rotation matrices have already been calculated
85      !! and placed in the A array.
86 <    
86 >
87      !! i and j are pointers to the two SSD atoms
88  
89      integer, intent(in) :: atom1, atom2
# Line 94 | Line 109 | contains
109      real (kind=dp) :: fxij, fyij, fzij, fxji, fyji, fzji      
110      real (kind=dp) :: fxradial, fyradial, fzradial
111      real (kind=dp) :: rijtest, rjitest
112 <      
112 >    real (kind=dp) :: radcomxi, radcomyi, radcomzi
113 >    real (kind=dp) :: radcomxj, radcomyj, radcomzj
114 >    integer :: id1, id2
115 >
116      if (.not.sticky_initialized) then
117         write(*,*) 'Sticky forces not initialized!'
118         return
119      endif
120  
121 <    r3 = r2*rij
104 <    r5 = r3*r2
105 <    
106 <    drdx = d(1) / rij
107 <    drdy = d(2) / rij
108 <    drdz = d(3) / rij
109 <    
110 < #ifdef IS_MPI
111 <    ! rotate the inter-particle separation into the two different
112 <    ! body-fixed coordinate systems:
113 <    
114 <    xi = A_row(1,atom1)*d(1) + A_row(2,atom1)*d(2) + A_row(3,atom1)*d(3)
115 <    yi = A_row(4,atom1)*d(1) + A_row(5,atom1)*d(2) + A_row(6,atom1)*d(3)
116 <    zi = A_row(7,atom1)*d(1) + A_row(8,atom1)*d(2) + A_row(9,atom1)*d(3)
117 <    
118 <    ! negative sign because this is the vector from j to i:
119 <    
120 <    xj = -(A_Col(1,atom2)*d(1) + A_Col(2,atom2)*d(2) + A_Col(3,atom2)*d(3))
121 <    yj = -(A_Col(4,atom2)*d(1) + A_Col(5,atom2)*d(2) + A_Col(6,atom2)*d(3))
122 <    zj = -(A_Col(7,atom2)*d(1) + A_Col(8,atom2)*d(2) + A_Col(9,atom2)*d(3))
123 < #else
124 <    ! rotate the inter-particle separation into the two different
125 <    ! body-fixed coordinate systems:
126 <    
127 <    xi = a(1,atom1)*d(1) + a(2,atom1)*d(2) + a(3,atom1)*d(3)
128 <    yi = a(4,atom1)*d(1) + a(5,atom1)*d(2) + a(6,atom1)*d(3)
129 <    zi = a(7,atom1)*d(1) + a(8,atom1)*d(2) + a(9,atom1)*d(3)
130 <    
131 <    ! negative sign because this is the vector from j to i:
132 <    
133 <    xj = -(a(1,atom2)*d(1) + a(2,atom2)*d(2) + a(3,atom2)*d(3))
134 <    yj = -(a(4,atom2)*d(1) + a(5,atom2)*d(2) + a(6,atom2)*d(3))
135 <    zj = -(a(7,atom2)*d(1) + a(8,atom2)*d(2) + a(9,atom2)*d(3))
136 < #endif
137 <    
138 <    xi2 = xi*xi
139 <    yi2 = yi*yi
140 <    zi2 = zi*zi
141 <    
142 <    xj2 = xj*xj
143 <    yj2 = yj*yj
144 <    zj2 = zj*zj
145 <  
146 <    call calc_sw_fnc(rij, s, sp, dsdr, dspdr)
147 <    
148 <    wi = 2.0d0*(xi2-yi2)*zi / r3
149 <    wj = 2.0d0*(xj2-yj2)*zj / r3
150 <    w = wi+wj
151 <    
152 <    zif = zi/rij - 0.6d0
153 <    zis = zi/rij + 0.8d0
154 <    
155 <    zjf = zj/rij - 0.6d0
156 <    zjs = zj/rij + 0.8d0
157 <    
158 <    wip = zif*zif*zis*zis - SSD_w0
159 <    wjp = zjf*zjf*zjs*zjs - SSD_w0
160 <    wp = wip + wjp
121 >    if ( rij .LE. SSD_rbig ) then
122  
123 <    if (do_pot) then
124 < #ifdef IS_MPI
125 <       pot_row(atom1) = pot_row(atom1) + 0.25d0*SSD_v0*(s*w + sp*wp)
126 <       pot_col(atom2) = pot_col(atom2) + 0.25d0*SSD_v0*(s*w + sp*wp)
127 < #else
128 <       pot = pot + 0.5d0*SSD_v0*(s*w + sp*wp)
129 < #endif  
169 <    endif
170 <    
171 <    dwidx =   4.0d0*xi*zi/r3  - 6.0d0*xi*zi*(xi2-yi2)/r5
172 <    dwidy = - 4.0d0*yi*zi/r3  - 6.0d0*yi*zi*(xi2-yi2)/r5
173 <    dwidz =   2.0d0*(xi2-yi2)/r3  - 6.0d0*zi2*(xi2-yi2)/r5
174 <    
175 <    dwjdx =   4.0d0*xj*zj/r3  - 6.0d0*xj*zj*(xj2-yj2)/r5
176 <    dwjdy = - 4.0d0*yj*zj/r3  - 6.0d0*yj*zj*(xj2-yj2)/r5
177 <    dwjdz =   2.0d0*(xj2-yj2)/r3  - 6.0d0*zj2*(xj2-yj2)/r5
178 <    
179 <    uglyi = zif*zif*zis + zif*zis*zis
180 <    uglyj = zjf*zjf*zjs + zjf*zjs*zjs
181 <    
182 <    dwipdx = -2.0d0*xi*zi*uglyi/r3
183 <    dwipdy = -2.0d0*yi*zi*uglyi/r3
184 <    dwipdz = 2.0d0*(1.0d0/rij - zi2/r3)*uglyi
185 <    
186 <    dwjpdx = -2.0d0*xj*zj*uglyj/r3
187 <    dwjpdy = -2.0d0*yj*zj*uglyj/r3
188 <    dwjpdz = 2.0d0*(1.0d0/rij - zj2/r3)*uglyj
189 <    
190 <    dwidux = 4.0d0*(yi*zi2 + 0.5d0*yi*(xi2-yi2))/r3
191 <    dwiduy = 4.0d0*(xi*zi2 - 0.5d0*xi*(xi2-yi2))/r3
192 <    dwiduz = - 8.0d0*xi*yi*zi/r3
193 <    
194 <    dwjdux = 4.0d0*(yj*zj2 + 0.5d0*yj*(xj2-yj2))/r3
195 <    dwjduy = 4.0d0*(xj*zj2 - 0.5d0*xj*(xj2-yj2))/r3
196 <    dwjduz = - 8.0d0*xj*yj*zj/r3
197 <    
198 <    dwipdux =  2.0d0*yi*uglyi/rij
199 <    dwipduy = -2.0d0*xi*uglyi/rij
200 <    dwipduz =  0.0d0
201 <    
202 <    dwjpdux =  2.0d0*yj*uglyj/rij
203 <    dwjpduy = -2.0d0*xj*uglyj/rij
204 <    dwjpduz =  0.0d0
205 <    
206 <    ! do the torques first since they are easy:
207 <    ! remember that these are still in the body fixed axes
208 <    
209 <    txi = 0.5d0*SSD_v0*(s*dwidux + sp*dwipdux)
210 <    tyi = 0.5d0*SSD_v0*(s*dwiduy + sp*dwipduy)
211 <    tzi = 0.5d0*SSD_v0*(s*dwiduz + sp*dwipduz)
212 <    
213 <    txj = 0.5d0*SSD_v0*(s*dwjdux + sp*dwjpdux)
214 <    tyj = 0.5d0*SSD_v0*(s*dwjduy + sp*dwjpduy)
215 <    tzj = 0.5d0*SSD_v0*(s*dwjduz + sp*dwjpduz)
216 <    
217 <    ! go back to lab frame using transpose of rotation matrix:
218 <  
123 >       r3 = r2*rij
124 >       r5 = r3*r2
125 >
126 >       drdx = d(1) / rij
127 >       drdy = d(2) / rij
128 >       drdz = d(3) / rij
129 >
130   #ifdef IS_MPI
131 <    t_Row(1,atom1) = t_Row(1,atom1) + a_Row(1,atom1)*txi + &
132 <         a_Row(4,atom1)*tyi + a_Row(7,atom1)*tzi
222 <    t_Row(2,atom1) = t_Row(2,atom1) + a_Row(2,atom1)*txi + &
223 <         a_Row(5,atom1)*tyi + a_Row(8,atom1)*tzi
224 <    t_Row(3,atom1) = t_Row(3,atom1) + a_Row(3,atom1)*txi + &
225 <         a_Row(6,atom1)*tyi + a_Row(9,atom1)*tzi
226 <    
227 <    t_Col(1,atom2) = t_Col(1,atom2) + a_Col(1,atom2)*txj + &
228 <         a_Col(4,atom2)*tyj + a_Col(7,atom2)*tzj
229 <    t_Col(2,atom2) = t_Col(2,atom2) + a_Col(2,atom2)*txj + &
230 <         a_Col(5,atom2)*tyj + a_Col(8,atom2)*tzj
231 <    t_Col(3,atom2) = t_Col(3,atom2) + a_Col(3,atom2)*txj + &
232 <         a_Col(6,atom2)*tyj + a_Col(9,atom2)*tzj
233 < #else
234 <    t(1,atom1) = t(1,atom1) + a(1,atom1)*txi + a(4,atom1)*tyi + a(7,atom1)*tzi
235 <    t(2,atom1) = t(2,atom1) + a(2,atom1)*txi + a(5,atom1)*tyi + a(8,atom1)*tzi
236 <    t(3,atom1) = t(3,atom1) + a(3,atom1)*txi + a(6,atom1)*tyi + a(9,atom1)*tzi
237 <    
238 <    t(1,atom2) = t(1,atom2) + a(1,atom2)*txj + a(4,atom2)*tyj + a(7,atom2)*tzj
239 <    t(2,atom2) = t(2,atom2) + a(2,atom2)*txj + a(5,atom2)*tyj + a(8,atom2)*tzj
240 <    t(3,atom2) = t(3,atom2) + a(3,atom2)*txj + a(6,atom2)*tyj + a(9,atom2)*tzj
241 < #endif    
242 <    ! Now, on to the forces:
243 <    
244 <    ! first rotate the i terms back into the lab frame:
131 >       ! rotate the inter-particle separation into the two different
132 >       ! body-fixed coordinate systems:
133  
134 < #ifdef IS_MPI    
135 <    fxii = a_Row(1,atom1)*(s*dwidx+sp*dwipdx) + &
136 <         a_Row(4,atom1)*(s*dwidy+sp*dwipdy) + &
249 <         a_Row(7,atom1)*(s*dwidz+sp*dwipdz)
250 <    fyii = a_Row(2,atom1)*(s*dwidx+sp*dwipdx) + &
251 <         a_Row(5,atom1)*(s*dwidy+sp*dwipdy) + &
252 <         a_Row(8,atom1)*(s*dwidz+sp*dwipdz)
253 <    fzii = a_Row(3,atom1)*(s*dwidx+sp*dwipdx) + &
254 <         a_Row(6,atom1)*(s*dwidy+sp*dwipdy) + &
255 <         a_Row(9,atom1)*(s*dwidz+sp*dwipdz)
134 >       xi = A_row(1,atom1)*d(1) + A_row(2,atom1)*d(2) + A_row(3,atom1)*d(3)
135 >       yi = A_row(4,atom1)*d(1) + A_row(5,atom1)*d(2) + A_row(6,atom1)*d(3)
136 >       zi = A_row(7,atom1)*d(1) + A_row(8,atom1)*d(2) + A_row(9,atom1)*d(3)
137  
138 <    fxjj = a_Col(1,atom2)*(s*dwjdx+sp*dwjpdx) + &
139 <         a_Col(4,atom2)*(s*dwjdy+sp*dwjpdy) + &
140 <         a_Col(7,atom2)*(s*dwjdz+sp*dwjpdz)
141 <    fyjj = a_Col(2,atom2)*(s*dwjdx+sp*dwjpdx) + &
142 <         a_Col(5,atom2)*(s*dwjdy+sp*dwjpdy) + &
262 <         a_Col(8,atom2)*(s*dwjdz+sp*dwjpdz)
263 <    fzjj = a_Col(3,atom2)*(s*dwjdx+sp*dwjpdx)+ &
264 <         a_Col(6,atom2)*(s*dwjdy+sp*dwjpdy) + &
265 <         a_Col(9,atom2)*(s*dwjdz+sp*dwjpdz)
138 >       ! negative sign because this is the vector from j to i:
139 >
140 >       xj = -(A_Col(1,atom2)*d(1) + A_Col(2,atom2)*d(2) + A_Col(3,atom2)*d(3))
141 >       yj = -(A_Col(4,atom2)*d(1) + A_Col(5,atom2)*d(2) + A_Col(6,atom2)*d(3))
142 >       zj = -(A_Col(7,atom2)*d(1) + A_Col(8,atom2)*d(2) + A_Col(9,atom2)*d(3))
143   #else
144 <    fxii = a(1,atom1)*(s*dwidx+sp*dwipdx) + &
145 <         a(4,atom1)*(s*dwidy+sp*dwipdy) + &
269 <         a(7,atom1)*(s*dwidz+sp*dwipdz)
270 <    fyii = a(2,atom1)*(s*dwidx+sp*dwipdx) + &
271 <         a(5,atom1)*(s*dwidy+sp*dwipdy) + &
272 <         a(8,atom1)*(s*dwidz+sp*dwipdz)
273 <    fzii = a(3,atom1)*(s*dwidx+sp*dwipdx) + &
274 <         a(6,atom1)*(s*dwidy+sp*dwipdy) + &
275 <         a(9,atom1)*(s*dwidz+sp*dwipdz)
144 >       ! rotate the inter-particle separation into the two different
145 >       ! body-fixed coordinate systems:
146  
147 <    fxjj = a(1,atom2)*(s*dwjdx+sp*dwjpdx) + &
148 <         a(4,atom2)*(s*dwjdy+sp*dwjpdy) + &
149 <         a(7,atom2)*(s*dwjdz+sp*dwjpdz)
150 <    fyjj = a(2,atom2)*(s*dwjdx+sp*dwjpdx) + &
151 <         a(5,atom2)*(s*dwjdy+sp*dwjpdy) + &
152 <         a(8,atom2)*(s*dwjdz+sp*dwjpdz)
153 <    fzjj = a(3,atom2)*(s*dwjdx+sp*dwjpdx)+ &
154 <         a(6,atom2)*(s*dwjdy+sp*dwjpdy) + &
155 <         a(9,atom2)*(s*dwjdz+sp*dwjpdz)
147 >       xi = a(1,atom1)*d(1) + a(2,atom1)*d(2) + a(3,atom1)*d(3)
148 >       yi = a(4,atom1)*d(1) + a(5,atom1)*d(2) + a(6,atom1)*d(3)
149 >       zi = a(7,atom1)*d(1) + a(8,atom1)*d(2) + a(9,atom1)*d(3)
150 >
151 >       ! negative sign because this is the vector from j to i:
152 >
153 >       xj = -(a(1,atom2)*d(1) + a(2,atom2)*d(2) + a(3,atom2)*d(3))
154 >       yj = -(a(4,atom2)*d(1) + a(5,atom2)*d(2) + a(6,atom2)*d(3))
155 >       zj = -(a(7,atom2)*d(1) + a(8,atom2)*d(2) + a(9,atom2)*d(3))
156   #endif
287    
288    fxij = -fxii
289    fyij = -fyii
290    fzij = -fzii
291        
292    fxji = -fxjj
293    fyji = -fyjj
294    fzji = -fzjj
295    
296    ! now assemble these with the radial-only terms:
157  
158 <    fxradial = 0.5d0*SSD_v0*(dsdr*drdx*w + dspdr*drdx*wp + fxii + fxji)
159 <    fyradial = 0.5d0*SSD_v0*(dsdr*drdy*w + dspdr*drdy*wp + fyii + fyji)
160 <    fzradial = 0.5d0*SSD_v0*(dsdr*drdz*w + dspdr*drdz*wp + fzii + fzji)
161 <      
162 < #ifdef IS_MPI
163 <    f_Row(1,atom1) = f_Row(1,atom1) + fxradial
164 <    f_Row(2,atom1) = f_Row(2,atom1) + fyradial
165 <    f_Row(3,atom1) = f_Row(3,atom1) + fzradial
166 <    
167 <    f_Col(1,atom2) = f_Col(1,atom2) - fxradial
168 <    f_Col(2,atom2) = f_Col(2,atom2) - fyradial
169 <    f_Col(3,atom2) = f_Col(3,atom2) - fzradial
158 >       xi2 = xi*xi
159 >       yi2 = yi*yi
160 >       zi2 = zi*zi
161 >
162 >       xj2 = xj*xj
163 >       yj2 = yj*yj
164 >       zj2 = zj*zj
165 >
166 >       call calc_sw_fnc(rij, s, sp, dsdr, dspdr)
167 >
168 >       wi = 2.0d0*(xi2-yi2)*zi / r3
169 >       wj = 2.0d0*(xj2-yj2)*zj / r3
170 >       w = wi+wj
171 >
172 >       zif = zi/rij - 0.6d0
173 >       zis = zi/rij + 0.8d0
174 >
175 >       zjf = zj/rij - 0.6d0
176 >       zjs = zj/rij + 0.8d0
177 >
178 >       wip = zif*zif*zis*zis - SSD_w0
179 >       wjp = zjf*zjf*zjs*zjs - SSD_w0
180 >       wp = wip + wjp
181 >
182 >       if (do_pot) then
183 > #ifdef IS_MPI
184 >          pot_row(atom1) = pot_row(atom1) + 0.25d0*(SSD_v0*s*w + SSD_v0p*sp*wp)
185 >          pot_col(atom2) = pot_col(atom2) + 0.25d0*(SSD_v0*s*w + SSD_v0p*sp*wp)
186   #else
187 <    f(1,atom1) = f(1,atom1) + fxradial
188 <    f(2,atom1) = f(2,atom1) + fyradial
189 <    f(3,atom1) = f(3,atom1) + fzradial
190 <    
191 <    f(1,atom2) = f(1,atom2) - fxradial
192 <    f(2,atom2) = f(2,atom2) - fyradial
193 <    f(3,atom2) = f(3,atom2) - fzradial
187 >          pot = pot + 0.5d0*(SSD_v0*s*w + SSD_v0p*sp*wp)
188 > #endif  
189 >       endif
190 >
191 >       dwidx =   4.0d0*xi*zi/r3  - 6.0d0*xi*zi*(xi2-yi2)/r5
192 >       dwidy = - 4.0d0*yi*zi/r3  - 6.0d0*yi*zi*(xi2-yi2)/r5
193 >       dwidz =   2.0d0*(xi2-yi2)/r3  - 6.0d0*zi2*(xi2-yi2)/r5
194 >
195 >       dwjdx =   4.0d0*xj*zj/r3  - 6.0d0*xj*zj*(xj2-yj2)/r5
196 >       dwjdy = - 4.0d0*yj*zj/r3  - 6.0d0*yj*zj*(xj2-yj2)/r5
197 >       dwjdz =   2.0d0*(xj2-yj2)/r3  - 6.0d0*zj2*(xj2-yj2)/r5
198 >
199 >       uglyi = zif*zif*zis + zif*zis*zis
200 >       uglyj = zjf*zjf*zjs + zjf*zjs*zjs
201 >
202 >       dwipdx = -2.0d0*xi*zi*uglyi/r3
203 >       dwipdy = -2.0d0*yi*zi*uglyi/r3
204 >       dwipdz = 2.0d0*(1.0d0/rij - zi2/r3)*uglyi
205 >
206 >       dwjpdx = -2.0d0*xj*zj*uglyj/r3
207 >       dwjpdy = -2.0d0*yj*zj*uglyj/r3
208 >       dwjpdz = 2.0d0*(1.0d0/rij - zj2/r3)*uglyj
209 >
210 >       dwidux = 4.0d0*(yi*zi2 + 0.5d0*yi*(xi2-yi2))/r3
211 >       dwiduy = 4.0d0*(xi*zi2 - 0.5d0*xi*(xi2-yi2))/r3
212 >       dwiduz = - 8.0d0*xi*yi*zi/r3
213 >
214 >       dwjdux = 4.0d0*(yj*zj2 + 0.5d0*yj*(xj2-yj2))/r3
215 >       dwjduy = 4.0d0*(xj*zj2 - 0.5d0*xj*(xj2-yj2))/r3
216 >       dwjduz = - 8.0d0*xj*yj*zj/r3
217 >
218 >       dwipdux =  2.0d0*yi*uglyi/rij
219 >       dwipduy = -2.0d0*xi*uglyi/rij
220 >       dwipduz =  0.0d0
221 >
222 >       dwjpdux =  2.0d0*yj*uglyj/rij
223 >       dwjpduy = -2.0d0*xj*uglyj/rij
224 >       dwjpduz =  0.0d0
225 >
226 >       ! do the torques first since they are easy:
227 >       ! remember that these are still in the body fixed axes
228 >
229 >       txi = 0.5d0*(SSD_v0*s*dwidux + SSD_v0p*sp*dwipdux)
230 >       tyi = 0.5d0*(SSD_v0*s*dwiduy + SSD_v0p*sp*dwipduy)
231 >       tzi = 0.5d0*(SSD_v0*s*dwiduz + SSD_v0p*sp*dwipduz)
232 >
233 >       txj = 0.5d0*(SSD_v0*s*dwjdux + SSD_v0p*sp*dwjpdux)
234 >       tyj = 0.5d0*(SSD_v0*s*dwjduy + SSD_v0p*sp*dwjpduy)
235 >       tzj = 0.5d0*(SSD_v0*s*dwjduz + SSD_v0p*sp*dwjpduz)
236 >
237 >       ! go back to lab frame using transpose of rotation matrix:
238 >
239 > #ifdef IS_MPI
240 >       t_Row(1,atom1) = t_Row(1,atom1) + a_Row(1,atom1)*txi + &
241 >            a_Row(4,atom1)*tyi + a_Row(7,atom1)*tzi
242 >       t_Row(2,atom1) = t_Row(2,atom1) + a_Row(2,atom1)*txi + &
243 >            a_Row(5,atom1)*tyi + a_Row(8,atom1)*tzi
244 >       t_Row(3,atom1) = t_Row(3,atom1) + a_Row(3,atom1)*txi + &
245 >            a_Row(6,atom1)*tyi + a_Row(9,atom1)*tzi
246 >
247 >       t_Col(1,atom2) = t_Col(1,atom2) + a_Col(1,atom2)*txj + &
248 >            a_Col(4,atom2)*tyj + a_Col(7,atom2)*tzj
249 >       t_Col(2,atom2) = t_Col(2,atom2) + a_Col(2,atom2)*txj + &
250 >            a_Col(5,atom2)*tyj + a_Col(8,atom2)*tzj
251 >       t_Col(3,atom2) = t_Col(3,atom2) + a_Col(3,atom2)*txj + &
252 >            a_Col(6,atom2)*tyj + a_Col(9,atom2)*tzj
253 > #else
254 >       t(1,atom1) = t(1,atom1) + a(1,atom1)*txi + a(4,atom1)*tyi + a(7,atom1)*tzi
255 >       t(2,atom1) = t(2,atom1) + a(2,atom1)*txi + a(5,atom1)*tyi + a(8,atom1)*tzi
256 >       t(3,atom1) = t(3,atom1) + a(3,atom1)*txi + a(6,atom1)*tyi + a(9,atom1)*tzi
257 >
258 >       t(1,atom2) = t(1,atom2) + a(1,atom2)*txj + a(4,atom2)*tyj + a(7,atom2)*tzj
259 >       t(2,atom2) = t(2,atom2) + a(2,atom2)*txj + a(5,atom2)*tyj + a(8,atom2)*tzj
260 >       t(3,atom2) = t(3,atom2) + a(3,atom2)*txj + a(6,atom2)*tyj + a(9,atom2)*tzj
261 > #endif    
262 >       ! Now, on to the forces:
263 >
264 >       ! first rotate the i terms back into the lab frame:
265 >
266 >       radcomxi = SSD_v0*s*dwidx+SSD_v0p*sp*dwipdx
267 >       radcomyi = SSD_v0*s*dwidy+SSD_v0p*sp*dwipdy
268 >       radcomzi = SSD_v0*s*dwidz+SSD_v0p*sp*dwipdz
269 >
270 >       radcomxj = SSD_v0*s*dwjdx+SSD_v0p*sp*dwjpdx
271 >       radcomyj = SSD_v0*s*dwjdy+SSD_v0p*sp*dwjpdy
272 >       radcomzj = SSD_v0*s*dwjdz+SSD_v0p*sp*dwjpdz
273 >
274 > #ifdef IS_MPI    
275 >       fxii = a_Row(1,atom1)*(radcomxi) + &
276 >            a_Row(4,atom1)*(radcomyi) + &
277 >            a_Row(7,atom1)*(radcomzi)
278 >       fyii = a_Row(2,atom1)*(radcomxi) + &
279 >            a_Row(5,atom1)*(radcomyi) + &
280 >            a_Row(8,atom1)*(radcomzi)
281 >       fzii = a_Row(3,atom1)*(radcomxi) + &
282 >            a_Row(6,atom1)*(radcomyi) + &
283 >            a_Row(9,atom1)*(radcomzi)
284 >
285 >       fxjj = a_Col(1,atom2)*(radcomxj) + &
286 >            a_Col(4,atom2)*(radcomyj) + &
287 >            a_Col(7,atom2)*(radcomzj)
288 >       fyjj = a_Col(2,atom2)*(radcomxj) + &
289 >            a_Col(5,atom2)*(radcomyj) + &
290 >            a_Col(8,atom2)*(radcomzj)
291 >       fzjj = a_Col(3,atom2)*(radcomxj)+ &
292 >            a_Col(6,atom2)*(radcomyj) + &
293 >            a_Col(9,atom2)*(radcomzj)
294 > #else
295 >       fxii = a(1,atom1)*(radcomxi) + &
296 >            a(4,atom1)*(radcomyi) + &
297 >            a(7,atom1)*(radcomzi)
298 >       fyii = a(2,atom1)*(radcomxi) + &
299 >            a(5,atom1)*(radcomyi) + &
300 >            a(8,atom1)*(radcomzi)
301 >       fzii = a(3,atom1)*(radcomxi) + &
302 >            a(6,atom1)*(radcomyi) + &
303 >            a(9,atom1)*(radcomzi)
304 >
305 >       fxjj = a(1,atom2)*(radcomxj) + &
306 >            a(4,atom2)*(radcomyj) + &
307 >            a(7,atom2)*(radcomzj)
308 >       fyjj = a(2,atom2)*(radcomxj) + &
309 >            a(5,atom2)*(radcomyj) + &
310 >            a(8,atom2)*(radcomzj)
311 >       fzjj = a(3,atom2)*(radcomxj)+ &
312 >            a(6,atom2)*(radcomyj) + &
313 >            a(9,atom2)*(radcomzj)
314   #endif
315 <    
316 <    if (do_stress) then          
317 <       if (molMembershipList(atom1) .ne. molMembershipList(atom2)) then
318 <          tau_Temp(1) = tau_Temp(1) + fxradial * d(1)
319 <          tau_Temp(2) = tau_Temp(2) + fxradial * d(2)
320 <          tau_Temp(3) = tau_Temp(3) + fxradial * d(3)
321 <          tau_Temp(4) = tau_Temp(4) + fyradial * d(1)
322 <          tau_Temp(5) = tau_Temp(5) + fyradial * d(2)
323 <          tau_Temp(6) = tau_Temp(6) + fyradial * d(3)
324 <          tau_Temp(7) = tau_Temp(7) + fzradial * d(1)
325 <          tau_Temp(8) = tau_Temp(8) + fzradial * d(2)
326 <          tau_Temp(9) = tau_Temp(9) + fzradial * d(3)
327 <          virial_Temp = virial_Temp + (tau_Temp(1) + tau_Temp(5) + tau_Temp(9))
315 >
316 >       fxij = -fxii
317 >       fyij = -fyii
318 >       fzij = -fzii
319 >
320 >       fxji = -fxjj
321 >       fyji = -fyjj
322 >       fzji = -fzjj
323 >
324 >       ! now assemble these with the radial-only terms:
325 >
326 >       fxradial = 0.5d0*(SSD_v0*dsdr*drdx*w + SSD_v0p*dspdr*drdx*wp + fxii + fxji)
327 >       fyradial = 0.5d0*(SSD_v0*dsdr*drdy*w + SSD_v0p*dspdr*drdy*wp + fyii + fyji)
328 >       fzradial = 0.5d0*(SSD_v0*dsdr*drdz*w + SSD_v0p*dspdr*drdz*wp + fzii + fzji)
329 >
330 > #ifdef IS_MPI
331 >       f_Row(1,atom1) = f_Row(1,atom1) + fxradial
332 >       f_Row(2,atom1) = f_Row(2,atom1) + fyradial
333 >       f_Row(3,atom1) = f_Row(3,atom1) + fzradial
334 >
335 >       f_Col(1,atom2) = f_Col(1,atom2) - fxradial
336 >       f_Col(2,atom2) = f_Col(2,atom2) - fyradial
337 >       f_Col(3,atom2) = f_Col(3,atom2) - fzradial
338 > #else
339 >       f(1,atom1) = f(1,atom1) + fxradial
340 >       f(2,atom1) = f(2,atom1) + fyradial
341 >       f(3,atom1) = f(3,atom1) + fzradial
342 >
343 >       f(1,atom2) = f(1,atom2) - fxradial
344 >       f(2,atom2) = f(2,atom2) - fyradial
345 >       f(3,atom2) = f(3,atom2) - fzradial
346 > #endif
347 >
348 > #ifdef IS_MPI
349 >          id1 = tagRow(atom1)
350 >          id2 = tagColumn(atom2)
351 > #else
352 >          id1 = atom1
353 >          id2 = atom2
354 > #endif
355 >
356 >       if (do_stress) then          
357 >          if (molMembershipList(id1) .ne. molMembershipList(id2)) then
358 >
359 >             ! because the d vector is the rj - ri vector, and
360 >             ! because fxradial, fyradial, and fzradial are the
361 >             ! (positive) force on atom i (negative on atom j) we need
362 >             ! a negative sign here:
363 >
364 >             tau_Temp(1) = tau_Temp(1) - d(1) * fxradial
365 >             tau_Temp(2) = tau_Temp(2) - d(1) * fyradial
366 >             tau_Temp(3) = tau_Temp(3) - d(1) * fzradial
367 >             tau_Temp(4) = tau_Temp(4) - d(2) * fxradial
368 >             tau_Temp(5) = tau_Temp(5) - d(2) * fyradial
369 >             tau_Temp(6) = tau_Temp(6) - d(2) * fzradial
370 >             tau_Temp(7) = tau_Temp(7) - d(3) * fxradial
371 >             tau_Temp(8) = tau_Temp(8) - d(3) * fyradial
372 >             tau_Temp(9) = tau_Temp(9) - d(3) * fzradial
373 >
374 >             virial_Temp = virial_Temp + (tau_Temp(1) + tau_Temp(5) + tau_Temp(9))
375 >          endif
376         endif
377      endif
378 <  
378 >
379    end subroutine do_sticky_pair
380  
381    !! calculates the switching functions and their derivatives for a given
382    subroutine calc_sw_fnc(r, s, sp, dsdr, dspdr)
383 <          
383 >    
384      real (kind=dp), intent(in) :: r
385      real (kind=dp), intent(inout) :: s, sp, dsdr, dspdr
386 <
386 >    
387      ! distances must be in angstroms
388      
389      if (r.lt.SSD_rl) then
390         s = 1.0d0
347       sp = 1.0d0
391         dsdr = 0.0d0
392 +    elseif (r.gt.SSD_ru) then
393 +       s = 0.0d0
394 +       dsdr = 0.0d0
395 +    else
396 +       s = ((SSD_ru + 2.0d0*r - 3.0d0*SSD_rl) * (SSD_ru-r)**2) / &
397 +            ((SSD_ru - SSD_rl)**3)
398 +       dsdr = 6.0d0*(r-SSD_ru)*(r-SSD_rl)/((SSD_ru - SSD_rl)**3)
399 +    endif
400 +
401 +    if (r.lt.SSD_rlp) then
402 +       sp = 1.0d0      
403         dspdr = 0.0d0
404      elseif (r.gt.SSD_rup) then
351       s = 0.0d0
405         sp = 0.0d0
353       dsdr = 0.0d0
406         dspdr = 0.0d0
407      else
408 <       sp = ((SSD_rup + 2.0d0*r - 3.0d0*SSD_rl) * (SSD_rup-r)**2) / &
409 <            ((SSD_rup - SSD_rl)**3)
410 <       dspdr = 6.0d0*(r-SSD_rup)*(r-SSD_rl)/((SSD_rup - SSD_rl)**3)
359 <      
360 <       if (r.gt.SSD_ru) then
361 <          s = 0.0d0
362 <          dsdr = 0.0d0
363 <       else
364 <          s = ((SSD_ru + 2.0d0*r - 3.0d0*SSD_rl) * (SSD_ru-r)**2) / &
365 <               ((SSD_ru - SSD_rl)**3)
366 <          dsdr = 6.0d0*(r-SSD_ru)*(r-SSD_rl)/((SSD_ru - SSD_rl)**3)
367 <       endif
408 >       sp = ((SSD_rup + 2.0d0*r - 3.0d0*SSD_rlp) * (SSD_rup-r)**2) / &
409 >            ((SSD_rup - SSD_rlp)**3)
410 >       dspdr = 6.0d0*(r-SSD_rup)*(r-SSD_rlp)/((SSD_rup - SSD_rlp)**3)      
411      endif
412      
413      return

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