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Revision 483 by gezelter, Wed Apr 9 04:06:43 2003 UTC vs.
Revision 635 by gezelter, Thu Jul 17 20:32:24 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 1.11 2003-07-17 20:32:24 gezelter Exp $, $Date: 2003-07-17 20:32:24 $, $Name: not supported by cvs2svn $, $Revision: 1.11 $
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  
36    public :: check_sticky_FF
# Line 44 | Line 46 | contains
46      return
47    end subroutine check_sticky_FF
48  
49 <  subroutine set_sticky_params(sticky_w0, sticky_v0)
50 <    real( kind = dp ), intent(in) :: sticky_w0, sticky_v0
49 >  subroutine set_sticky_params(sticky_w0, sticky_v0, sticky_v0p, &
50 >       sticky_rl, sticky_ru, sticky_rlp, sticky_rup)
51 >
52 >    real( kind = dp ), intent(in) :: sticky_w0, sticky_v0, sticky_v0p
53 >    real( kind = dp ), intent(in) :: sticky_rl, sticky_ru
54 >    real( kind = dp ), intent(in) :: sticky_rlp, sticky_rup
55      
56      ! we could pass all 5 parameters if we felt like it...
57      
58      SSD_w0 = sticky_w0
59      SSD_v0 = sticky_v0
60 <    SSD_rl = 2.75_DP
61 <    SSD_ru = 3.35_DP
62 <    SSD_rup = 4.0_DP
60 >    SSD_v0p = sticky_v0p
61 >    SSD_rl = sticky_rl
62 >    SSD_ru = sticky_ru
63 >    SSD_rlp = sticky_rlp
64 >    SSD_rup = sticky_rup
65    
66      sticky_initialized = .true.
67      return
# Line 61 | Line 69 | contains
69  
70    subroutine do_sticky_pair(atom1, atom2, d, rij, r2, A, pot, f, t, &
71         do_pot, do_stress)
72 <    
72 >
73      !! This routine does only the sticky portion of the SSD potential
74      !! [Chandra and Ichiye, J. Chem. Phys. 111, 2701 (1999)].
75      !! The Lennard-Jones and dipolar interaction must be handled separately.
76 <    
76 >
77      !! We assume that the rotation matrices have already been calculated
78      !! and placed in the A array.
79 <    
79 >
80      !! i and j are pointers to the two SSD atoms
81  
82      integer, intent(in) :: atom1, atom2
# Line 94 | Line 102 | contains
102      real (kind=dp) :: fxij, fyij, fzij, fxji, fyji, fzji      
103      real (kind=dp) :: fxradial, fyradial, fzradial
104      real (kind=dp) :: rijtest, rjitest
105 <      
105 >    real (kind=dp) :: radcomxi, radcomyi, radcomzi
106 >    real (kind=dp) :: radcomxj, radcomyj, radcomzj
107 >
108 >
109      if (.not.sticky_initialized) then
110         write(*,*) 'Sticky forces not initialized!'
111         return
112      endif
113  
114 <    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
114 >    if ( rij .LE. SSD_rup ) then
115  
116 <    if (do_pot) then
117 < #ifdef IS_MPI
118 <       pot_row(atom1) = pot_row(atom1) + 0.25d0*SSD_v0*(s*w + sp*wp)
119 <       pot_col(atom2) = pot_col(atom2) + 0.25d0*SSD_v0*(s*w + sp*wp)
120 < #else
121 <       pot = pot + 0.5d0*SSD_v0*(s*w + sp*wp)
122 < #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 <  
116 >       r3 = r2*rij
117 >       r5 = r3*r2
118 >
119 >       drdx = d(1) / rij
120 >       drdy = d(2) / rij
121 >       drdz = d(3) / rij
122 >
123   #ifdef IS_MPI
124 <    t_Row(1,atom1) = t_Row(1,atom1) + a_Row(1,atom1)*txi + &
125 <         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:
124 >       ! rotate the inter-particle separation into the two different
125 >       ! body-fixed coordinate systems:
126  
127 < #ifdef IS_MPI    
128 <    fxii = a_Row(1,atom1)*(s*dwidx+sp*dwipdx) + &
129 <         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)
127 >       xi = A_row(1,atom1)*d(1) + A_row(2,atom1)*d(2) + A_row(3,atom1)*d(3)
128 >       yi = A_row(4,atom1)*d(1) + A_row(5,atom1)*d(2) + A_row(6,atom1)*d(3)
129 >       zi = A_row(7,atom1)*d(1) + A_row(8,atom1)*d(2) + A_row(9,atom1)*d(3)
130  
131 <    fxjj = a_Col(1,atom2)*(s*dwjdx+sp*dwjpdx) + &
132 <         a_Col(4,atom2)*(s*dwjdy+sp*dwjpdy) + &
133 <         a_Col(7,atom2)*(s*dwjdz+sp*dwjpdz)
134 <    fyjj = a_Col(2,atom2)*(s*dwjdx+sp*dwjpdx) + &
135 <         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)
131 >       ! negative sign because this is the vector from j to i:
132 >
133 >       xj = -(A_Col(1,atom2)*d(1) + A_Col(2,atom2)*d(2) + A_Col(3,atom2)*d(3))
134 >       yj = -(A_Col(4,atom2)*d(1) + A_Col(5,atom2)*d(2) + A_Col(6,atom2)*d(3))
135 >       zj = -(A_Col(7,atom2)*d(1) + A_Col(8,atom2)*d(2) + A_Col(9,atom2)*d(3))
136   #else
137 <    fxii = a(1,atom1)*(s*dwidx+sp*dwipdx) + &
138 <         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)
137 >       ! rotate the inter-particle separation into the two different
138 >       ! body-fixed coordinate systems:
139  
140 <    fxjj = a(1,atom2)*(s*dwjdx+sp*dwjpdx) + &
141 <         a(4,atom2)*(s*dwjdy+sp*dwjpdy) + &
142 <         a(7,atom2)*(s*dwjdz+sp*dwjpdz)
143 <    fyjj = a(2,atom2)*(s*dwjdx+sp*dwjpdx) + &
144 <         a(5,atom2)*(s*dwjdy+sp*dwjpdy) + &
145 <         a(8,atom2)*(s*dwjdz+sp*dwjpdz)
146 <    fzjj = a(3,atom2)*(s*dwjdx+sp*dwjpdx)+ &
147 <         a(6,atom2)*(s*dwjdy+sp*dwjpdy) + &
148 <         a(9,atom2)*(s*dwjdz+sp*dwjpdz)
140 >       xi = a(1,atom1)*d(1) + a(2,atom1)*d(2) + a(3,atom1)*d(3)
141 >       yi = a(4,atom1)*d(1) + a(5,atom1)*d(2) + a(6,atom1)*d(3)
142 >       zi = a(7,atom1)*d(1) + a(8,atom1)*d(2) + a(9,atom1)*d(3)
143 >
144 >       ! negative sign because this is the vector from j to i:
145 >
146 >       xj = -(a(1,atom2)*d(1) + a(2,atom2)*d(2) + a(3,atom2)*d(3))
147 >       yj = -(a(4,atom2)*d(1) + a(5,atom2)*d(2) + a(6,atom2)*d(3))
148 >       zj = -(a(7,atom2)*d(1) + a(8,atom2)*d(2) + a(9,atom2)*d(3))
149   #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:
150  
151 <    fxradial = 0.5d0*SSD_v0*(dsdr*drdx*w + dspdr*drdx*wp + fxii + fxji)
152 <    fyradial = 0.5d0*SSD_v0*(dsdr*drdy*w + dspdr*drdy*wp + fyii + fyji)
153 <    fzradial = 0.5d0*SSD_v0*(dsdr*drdz*w + dspdr*drdz*wp + fzii + fzji)
154 <      
155 < #ifdef IS_MPI
156 <    f_Row(1,atom1) = f_Row(1,atom1) + fxradial
157 <    f_Row(2,atom1) = f_Row(2,atom1) + fyradial
158 <    f_Row(3,atom1) = f_Row(3,atom1) + fzradial
159 <    
160 <    f_Col(1,atom2) = f_Col(1,atom2) - fxradial
161 <    f_Col(2,atom2) = f_Col(2,atom2) - fyradial
162 <    f_Col(3,atom2) = f_Col(3,atom2) - fzradial
151 >       xi2 = xi*xi
152 >       yi2 = yi*yi
153 >       zi2 = zi*zi
154 >
155 >       xj2 = xj*xj
156 >       yj2 = yj*yj
157 >       zj2 = zj*zj
158 >
159 >       call calc_sw_fnc(rij, s, sp, dsdr, dspdr)
160 >
161 >       wi = 2.0d0*(xi2-yi2)*zi / r3
162 >       wj = 2.0d0*(xj2-yj2)*zj / r3
163 >       w = wi+wj
164 >
165 >       zif = zi/rij - 0.6d0
166 >       zis = zi/rij + 0.8d0
167 >
168 >       zjf = zj/rij - 0.6d0
169 >       zjs = zj/rij + 0.8d0
170 >
171 >       wip = zif*zif*zis*zis - SSD_w0
172 >       wjp = zjf*zjf*zjs*zjs - SSD_w0
173 >       wp = wip + wjp
174 >
175 >       if (do_pot) then
176 > #ifdef IS_MPI
177 >          pot_row(atom1) = pot_row(atom1) + 0.25d0*(SSD_v0*s*w + SSD_v0p*sp*wp)
178 >          pot_col(atom2) = pot_col(atom2) + 0.25d0*(SSD_v0*s*w + SSD_v0p*sp*wp)
179   #else
180 <    f(1,atom1) = f(1,atom1) + fxradial
181 <    f(2,atom1) = f(2,atom1) + fyradial
182 <    f(3,atom1) = f(3,atom1) + fzradial
183 <    
184 <    f(1,atom2) = f(1,atom2) - fxradial
185 <    f(2,atom2) = f(2,atom2) - fyradial
186 <    f(3,atom2) = f(3,atom2) - fzradial
180 >          pot = pot + 0.5d0*(SSD_v0*s*w + SSD_v0p*sp*wp)
181 > #endif  
182 >       endif
183 >
184 >       dwidx =   4.0d0*xi*zi/r3  - 6.0d0*xi*zi*(xi2-yi2)/r5
185 >       dwidy = - 4.0d0*yi*zi/r3  - 6.0d0*yi*zi*(xi2-yi2)/r5
186 >       dwidz =   2.0d0*(xi2-yi2)/r3  - 6.0d0*zi2*(xi2-yi2)/r5
187 >
188 >       dwjdx =   4.0d0*xj*zj/r3  - 6.0d0*xj*zj*(xj2-yj2)/r5
189 >       dwjdy = - 4.0d0*yj*zj/r3  - 6.0d0*yj*zj*(xj2-yj2)/r5
190 >       dwjdz =   2.0d0*(xj2-yj2)/r3  - 6.0d0*zj2*(xj2-yj2)/r5
191 >
192 >       uglyi = zif*zif*zis + zif*zis*zis
193 >       uglyj = zjf*zjf*zjs + zjf*zjs*zjs
194 >
195 >       dwipdx = -2.0d0*xi*zi*uglyi/r3
196 >       dwipdy = -2.0d0*yi*zi*uglyi/r3
197 >       dwipdz = 2.0d0*(1.0d0/rij - zi2/r3)*uglyi
198 >
199 >       dwjpdx = -2.0d0*xj*zj*uglyj/r3
200 >       dwjpdy = -2.0d0*yj*zj*uglyj/r3
201 >       dwjpdz = 2.0d0*(1.0d0/rij - zj2/r3)*uglyj
202 >
203 >       dwidux = 4.0d0*(yi*zi2 + 0.5d0*yi*(xi2-yi2))/r3
204 >       dwiduy = 4.0d0*(xi*zi2 - 0.5d0*xi*(xi2-yi2))/r3
205 >       dwiduz = - 8.0d0*xi*yi*zi/r3
206 >
207 >       dwjdux = 4.0d0*(yj*zj2 + 0.5d0*yj*(xj2-yj2))/r3
208 >       dwjduy = 4.0d0*(xj*zj2 - 0.5d0*xj*(xj2-yj2))/r3
209 >       dwjduz = - 8.0d0*xj*yj*zj/r3
210 >
211 >       dwipdux =  2.0d0*yi*uglyi/rij
212 >       dwipduy = -2.0d0*xi*uglyi/rij
213 >       dwipduz =  0.0d0
214 >
215 >       dwjpdux =  2.0d0*yj*uglyj/rij
216 >       dwjpduy = -2.0d0*xj*uglyj/rij
217 >       dwjpduz =  0.0d0
218 >
219 >       ! do the torques first since they are easy:
220 >       ! remember that these are still in the body fixed axes
221 >
222 >       txi = 0.5d0*(SSD_v0*s*dwidux + SSD_v0p*sp*dwipdux)
223 >       tyi = 0.5d0*(SSD_v0*s*dwiduy + SSD_v0p*sp*dwipduy)
224 >       tzi = 0.5d0*(SSD_v0*s*dwiduz + SSD_v0p*sp*dwipduz)
225 >
226 >       txj = 0.5d0*(SSD_v0*s*dwjdux + SSD_v0p*sp*dwjpdux)
227 >       tyj = 0.5d0*(SSD_v0*s*dwjduy + SSD_v0p*sp*dwjpduy)
228 >       tzj = 0.5d0*(SSD_v0*s*dwjduz + SSD_v0p*sp*dwjpduz)
229 >
230 >       ! go back to lab frame using transpose of rotation matrix:
231 >
232 > #ifdef IS_MPI
233 >       t_Row(1,atom1) = t_Row(1,atom1) + a_Row(1,atom1)*txi + &
234 >            a_Row(4,atom1)*tyi + a_Row(7,atom1)*tzi
235 >       t_Row(2,atom1) = t_Row(2,atom1) + a_Row(2,atom1)*txi + &
236 >            a_Row(5,atom1)*tyi + a_Row(8,atom1)*tzi
237 >       t_Row(3,atom1) = t_Row(3,atom1) + a_Row(3,atom1)*txi + &
238 >            a_Row(6,atom1)*tyi + a_Row(9,atom1)*tzi
239 >
240 >       t_Col(1,atom2) = t_Col(1,atom2) + a_Col(1,atom2)*txj + &
241 >            a_Col(4,atom2)*tyj + a_Col(7,atom2)*tzj
242 >       t_Col(2,atom2) = t_Col(2,atom2) + a_Col(2,atom2)*txj + &
243 >            a_Col(5,atom2)*tyj + a_Col(8,atom2)*tzj
244 >       t_Col(3,atom2) = t_Col(3,atom2) + a_Col(3,atom2)*txj + &
245 >            a_Col(6,atom2)*tyj + a_Col(9,atom2)*tzj
246 > #else
247 >       t(1,atom1) = t(1,atom1) + a(1,atom1)*txi + a(4,atom1)*tyi + a(7,atom1)*tzi
248 >       t(2,atom1) = t(2,atom1) + a(2,atom1)*txi + a(5,atom1)*tyi + a(8,atom1)*tzi
249 >       t(3,atom1) = t(3,atom1) + a(3,atom1)*txi + a(6,atom1)*tyi + a(9,atom1)*tzi
250 >
251 >       t(1,atom2) = t(1,atom2) + a(1,atom2)*txj + a(4,atom2)*tyj + a(7,atom2)*tzj
252 >       t(2,atom2) = t(2,atom2) + a(2,atom2)*txj + a(5,atom2)*tyj + a(8,atom2)*tzj
253 >       t(3,atom2) = t(3,atom2) + a(3,atom2)*txj + a(6,atom2)*tyj + a(9,atom2)*tzj
254 > #endif    
255 >       ! Now, on to the forces:
256 >
257 >       ! first rotate the i terms back into the lab frame:
258 >
259 >       radcomxi = SSD_v0*s*dwidx+SSD_v0p*sp*dwipdx
260 >       radcomyi = SSD_v0*s*dwidy+SSD_v0p*sp*dwipdy
261 >       radcomzi = SSD_v0*s*dwidz+SSD_v0p*sp*dwipdz
262 >
263 >       radcomxj = SSD_v0*s*dwjdx+SSD_v0p*sp*dwjpdx
264 >       radcomyj = SSD_v0*s*dwjdy+SSD_v0p*sp*dwjpdy
265 >       radcomzj = SSD_v0*s*dwjdz+SSD_v0p*sp*dwjpdz
266 >
267 > #ifdef IS_MPI    
268 >       fxii = a_Row(1,atom1)*(radcomxi) + &
269 >            a_Row(4,atom1)*(radcomyi) + &
270 >            a_Row(7,atom1)*(radcomzi)
271 >       fyii = a_Row(2,atom1)*(radcomxi) + &
272 >            a_Row(5,atom1)*(radcomyi) + &
273 >            a_Row(8,atom1)*(radcomzi)
274 >       fzii = a_Row(3,atom1)*(radcomxi) + &
275 >            a_Row(6,atom1)*(radcomyi) + &
276 >            a_Row(9,atom1)*(radcomzi)
277 >
278 >       fxjj = a_Col(1,atom2)*(radcomxj) + &
279 >            a_Col(4,atom2)*(radcomyj) + &
280 >            a_Col(7,atom2)*(radcomzj)
281 >       fyjj = a_Col(2,atom2)*(radcomxj) + &
282 >            a_Col(5,atom2)*(radcomyj) + &
283 >            a_Col(8,atom2)*(radcomzj)
284 >       fzjj = a_Col(3,atom2)*(radcomxj)+ &
285 >            a_Col(6,atom2)*(radcomyj) + &
286 >            a_Col(9,atom2)*(radcomzj)
287 > #else
288 >       fxii = a(1,atom1)*(radcomxi) + &
289 >            a(4,atom1)*(radcomyi) + &
290 >            a(7,atom1)*(radcomzi)
291 >       fyii = a(2,atom1)*(radcomxi) + &
292 >            a(5,atom1)*(radcomyi) + &
293 >            a(8,atom1)*(radcomzi)
294 >       fzii = a(3,atom1)*(radcomxi) + &
295 >            a(6,atom1)*(radcomyi) + &
296 >            a(9,atom1)*(radcomzi)
297 >
298 >       fxjj = a(1,atom2)*(radcomxj) + &
299 >            a(4,atom2)*(radcomyj) + &
300 >            a(7,atom2)*(radcomzj)
301 >       fyjj = a(2,atom2)*(radcomxj) + &
302 >            a(5,atom2)*(radcomyj) + &
303 >            a(8,atom2)*(radcomzj)
304 >       fzjj = a(3,atom2)*(radcomxj)+ &
305 >            a(6,atom2)*(radcomyj) + &
306 >            a(9,atom2)*(radcomzj)
307   #endif
308 <    
309 <    if (do_stress) then          
310 <       if (molMembershipList(atom1) .ne. molMembershipList(atom2)) then
311 <          tau_Temp(1) = tau_Temp(1) + fxradial * d(1)
312 <          tau_Temp(2) = tau_Temp(2) + fxradial * d(2)
313 <          tau_Temp(3) = tau_Temp(3) + fxradial * d(3)
314 <          tau_Temp(4) = tau_Temp(4) + fyradial * d(1)
315 <          tau_Temp(5) = tau_Temp(5) + fyradial * d(2)
316 <          tau_Temp(6) = tau_Temp(6) + fyradial * d(3)
317 <          tau_Temp(7) = tau_Temp(7) + fzradial * d(1)
318 <          tau_Temp(8) = tau_Temp(8) + fzradial * d(2)
319 <          tau_Temp(9) = tau_Temp(9) + fzradial * d(3)
320 <          virial_Temp = virial_Temp + (tau_Temp(1) + tau_Temp(5) + tau_Temp(9))
308 >
309 >       fxij = -fxii
310 >       fyij = -fyii
311 >       fzij = -fzii
312 >
313 >       fxji = -fxjj
314 >       fyji = -fyjj
315 >       fzji = -fzjj
316 >
317 >       ! now assemble these with the radial-only terms:
318 >
319 >       fxradial = 0.5d0*(SSD_v0*dsdr*drdx*w + SSD_v0p*dspdr*drdx*wp + fxii + fxji)
320 >       fyradial = 0.5d0*(SSD_v0*dsdr*drdy*w + SSD_v0p*dspdr*drdy*wp + fyii + fyji)
321 >       fzradial = 0.5d0*(SSD_v0*dsdr*drdz*w + SSD_v0p*dspdr*drdz*wp + fzii + fzji)
322 >
323 > #ifdef IS_MPI
324 >       f_Row(1,atom1) = f_Row(1,atom1) + fxradial
325 >       f_Row(2,atom1) = f_Row(2,atom1) + fyradial
326 >       f_Row(3,atom1) = f_Row(3,atom1) + fzradial
327 >
328 >       f_Col(1,atom2) = f_Col(1,atom2) - fxradial
329 >       f_Col(2,atom2) = f_Col(2,atom2) - fyradial
330 >       f_Col(3,atom2) = f_Col(3,atom2) - fzradial
331 > #else
332 >       f(1,atom1) = f(1,atom1) + fxradial
333 >       f(2,atom1) = f(2,atom1) + fyradial
334 >       f(3,atom1) = f(3,atom1) + fzradial
335 >
336 >       f(1,atom2) = f(1,atom2) - fxradial
337 >       f(2,atom2) = f(2,atom2) - fyradial
338 >       f(3,atom2) = f(3,atom2) - fzradial
339 > #endif
340 >
341 >       if (do_stress) then          
342 >          if (molMembershipList(atom1) .ne. molMembershipList(atom2)) then
343 >
344 >             ! because the d vector is the rj - ri vector, and
345 >             ! because fxradial, fyradial, and fzradial are the
346 >             ! (positive) force on atom i (negative on atom j) we need
347 >             ! a negative sign here:
348 >
349 >             tau_Temp(1) = tau_Temp(1) - d(1) * fxradial
350 >             tau_Temp(2) = tau_Temp(2) - d(1) * fyradial
351 >             tau_Temp(3) = tau_Temp(3) - d(1) * fzradial
352 >             tau_Temp(4) = tau_Temp(4) - d(2) * fxradial
353 >             tau_Temp(5) = tau_Temp(5) - d(2) * fyradial
354 >             tau_Temp(6) = tau_Temp(6) - d(2) * fzradial
355 >             tau_Temp(7) = tau_Temp(7) - d(3) * fxradial
356 >             tau_Temp(8) = tau_Temp(8) - d(3) * fyradial
357 >             tau_Temp(9) = tau_Temp(9) - d(3) * fzradial
358 >
359 >             virial_Temp = virial_Temp + (tau_Temp(1) + tau_Temp(5) + tau_Temp(9))
360 >          endif
361         endif
362      endif
363 <  
363 >
364    end subroutine do_sticky_pair
365  
366    !! calculates the switching functions and their derivatives for a given
367    subroutine calc_sw_fnc(r, s, sp, dsdr, dspdr)
368 <          
368 >    
369      real (kind=dp), intent(in) :: r
370      real (kind=dp), intent(inout) :: s, sp, dsdr, dspdr
371 <
371 >    
372      ! distances must be in angstroms
373      
374      if (r.lt.SSD_rl) then
375         s = 1.0d0
347       sp = 1.0d0
376         dsdr = 0.0d0
377 +    elseif (r.gt.SSD_ru) then
378 +       s = 0.0d0
379 +       dsdr = 0.0d0
380 +    else
381 +       s = ((SSD_ru + 2.0d0*r - 3.0d0*SSD_rl) * (SSD_ru-r)**2) / &
382 +            ((SSD_ru - SSD_rl)**3)
383 +       dsdr = 6.0d0*(r-SSD_ru)*(r-SSD_rl)/((SSD_ru - SSD_rl)**3)
384 +    endif
385 +
386 +    if (r.lt.SSD_rlp) then
387 +       sp = 1.0d0      
388         dspdr = 0.0d0
389      elseif (r.gt.SSD_rup) then
351       s = 0.0d0
390         sp = 0.0d0
353       dsdr = 0.0d0
391         dspdr = 0.0d0
392      else
393 <       sp = ((SSD_rup + 2.0d0*r - 3.0d0*SSD_rl) * (SSD_rup-r)**2) / &
394 <            ((SSD_rup - SSD_rl)**3)
395 <       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
393 >       sp = ((SSD_rup + 2.0d0*r - 3.0d0*SSD_rlp) * (SSD_rup-r)**2) / &
394 >            ((SSD_rup - SSD_rlp)**3)
395 >       dspdr = 6.0d0*(r-SSD_rup)*(r-SSD_rlp)/((SSD_rup - SSD_rlp)**3)      
396      endif
397      
398      return

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