| 1 |
!! Calculates Long Range forces Lennard-Jones interactions. |
| 2 |
!! Corresponds to the force field defined in lj_FF.cpp |
| 3 |
!! @author Charles F. Vardeman II |
| 4 |
!! @author Matthew Meineke |
| 5 |
!! @version $Id: calc_LJ_FF.F90,v 1.21 2004-05-27 00:48:12 tim Exp $, $Date: 2004-05-27 00:48:12 $, $Name: not supported by cvs2svn $, $Revision: 1.21 $ |
| 6 |
|
| 7 |
module lj |
| 8 |
use definitions |
| 9 |
use atype_module |
| 10 |
use switcheroo |
| 11 |
use vector_class |
| 12 |
use simulation |
| 13 |
#ifdef IS_MPI |
| 14 |
use mpiSimulation |
| 15 |
#endif |
| 16 |
use force_globals |
| 17 |
|
| 18 |
implicit none |
| 19 |
PRIVATE |
| 20 |
|
| 21 |
#define __FORTRAN90 |
| 22 |
#include "fForceField.h" |
| 23 |
|
| 24 |
integer, save :: LJ_Mixing_Policy |
| 25 |
real(kind=DP), save :: LJ_rcut |
| 26 |
logical, save :: havePolicy = .false. |
| 27 |
logical, save :: haveCut = .false. |
| 28 |
logical, save :: LJ_do_shift = .false. |
| 29 |
|
| 30 |
!! Logical has lj force field module been initialized? |
| 31 |
|
| 32 |
logical, save :: LJ_FF_initialized = .false. |
| 33 |
|
| 34 |
!! Public methods and data |
| 35 |
public :: init_LJ_FF |
| 36 |
public :: setCutoffLJ |
| 37 |
public :: do_lj_pair |
| 38 |
|
| 39 |
type :: lj_mixed_params |
| 40 |
!! Lennard-Jones epsilon |
| 41 |
real ( kind = dp ) :: epsilon = 0.0_dp |
| 42 |
!! Lennard-Jones Sigma |
| 43 |
real ( kind = dp ) :: sigma = 0.0_dp |
| 44 |
!! Lennard-Jones Sigma to sixth |
| 45 |
real ( kind = dp ) :: sigma6 = 0.0_dp |
| 46 |
!! |
| 47 |
real ( kind = dp ) :: tp6 |
| 48 |
real ( kind = dp ) :: tp12 |
| 49 |
real ( kind = dp ) :: delta = 0.0_dp |
| 50 |
end type lj_mixed_params |
| 51 |
|
| 52 |
type (lj_mixed_params), dimension(:,:), pointer :: ljMixed |
| 53 |
|
| 54 |
contains |
| 55 |
|
| 56 |
subroutine init_LJ_FF(mix_Policy, status) |
| 57 |
integer, intent(in) :: mix_Policy |
| 58 |
integer, intent(out) :: status |
| 59 |
integer :: myStatus |
| 60 |
|
| 61 |
if (mix_Policy == LB_MIXING_RULE) then |
| 62 |
LJ_Mixing_Policy = LB_MIXING_RULE |
| 63 |
else |
| 64 |
if (mix_Policy == EXPLICIT_MIXING_RULE) then |
| 65 |
LJ_Mixing_Policy = EXPLICIT_MIXING_RULE |
| 66 |
else |
| 67 |
write(*,*) 'Unknown Mixing Policy!' |
| 68 |
status = -1 |
| 69 |
return |
| 70 |
endif |
| 71 |
endif |
| 72 |
|
| 73 |
havePolicy = .true. |
| 74 |
|
| 75 |
if (haveCut) then |
| 76 |
status = 0 |
| 77 |
call createMixingList(myStatus) |
| 78 |
if (myStatus /= 0) then |
| 79 |
status = -1 |
| 80 |
return |
| 81 |
end if |
| 82 |
|
| 83 |
LJ_FF_initialized = .true. |
| 84 |
end if |
| 85 |
|
| 86 |
end subroutine init_LJ_FF |
| 87 |
|
| 88 |
subroutine setCutoffLJ(rcut, do_shift, status) |
| 89 |
logical, intent(in):: do_shift |
| 90 |
integer :: status, myStatus |
| 91 |
real(kind=dp) :: rcut |
| 92 |
|
| 93 |
#define __FORTRAN90 |
| 94 |
#include "fSwitchingFunction.h" |
| 95 |
|
| 96 |
status = 0 |
| 97 |
|
| 98 |
LJ_rcut = rcut |
| 99 |
LJ_do_shift = do_shift |
| 100 |
call set_switch(LJ_SWITCH, rcut, rcut) |
| 101 |
haveCut = .true. |
| 102 |
|
| 103 |
if (havePolicy) then |
| 104 |
status = 0 |
| 105 |
call createMixingList(myStatus) |
| 106 |
if (myStatus /= 0) then |
| 107 |
status = -1 |
| 108 |
return |
| 109 |
end if |
| 110 |
|
| 111 |
LJ_FF_initialized = .true. |
| 112 |
end if |
| 113 |
|
| 114 |
return |
| 115 |
end subroutine setCutoffLJ |
| 116 |
|
| 117 |
subroutine createMixingList(status) |
| 118 |
integer :: nAtypes |
| 119 |
integer :: status |
| 120 |
integer :: i |
| 121 |
integer :: j |
| 122 |
real ( kind = dp ) :: mySigma_i,mySigma_j |
| 123 |
real ( kind = dp ) :: myEpsilon_i,myEpsilon_j |
| 124 |
real ( kind = dp ) :: rcut6 |
| 125 |
status = 0 |
| 126 |
|
| 127 |
nAtypes = getSize(atypes) |
| 128 |
if (nAtypes == 0) then |
| 129 |
status = -1 |
| 130 |
return |
| 131 |
end if |
| 132 |
|
| 133 |
if (.not. associated(ljMixed)) then |
| 134 |
allocate(ljMixed(nAtypes, nAtypes)) |
| 135 |
endif |
| 136 |
|
| 137 |
rcut6 = LJ_rcut**6 |
| 138 |
|
| 139 |
! This loops through all atypes, even those that don't support LJ forces. |
| 140 |
do i = 1, nAtypes |
| 141 |
|
| 142 |
call getElementProperty(atypes, i, "lj_epsilon", myEpsilon_i) |
| 143 |
call getElementProperty(atypes, i, "lj_sigma", mySigma_i) |
| 144 |
! do self mixing rule |
| 145 |
ljMixed(i,i)%sigma = mySigma_i |
| 146 |
|
| 147 |
ljMixed(i,i)%sigma6 = (ljMixed(i,i)%sigma) ** 6 |
| 148 |
|
| 149 |
ljMixed(i,i)%tp6 = (ljMixed(i,i)%sigma6)/rcut6 |
| 150 |
|
| 151 |
ljMixed(i,i)%tp12 = (ljMixed(i,i)%tp6) ** 2 |
| 152 |
|
| 153 |
|
| 154 |
ljMixed(i,i)%epsilon = myEpsilon_i |
| 155 |
|
| 156 |
ljMixed(i,i)%delta = -4.0_DP * ljMixed(i,i)%epsilon * & |
| 157 |
(ljMixed(i,i)%tp12 - ljMixed(i,i)%tp6) |
| 158 |
|
| 159 |
do j = i + 1, nAtypes |
| 160 |
call getElementProperty(atypes,j,"lj_epsilon",myEpsilon_j) |
| 161 |
call getElementProperty(atypes,j,"lj_sigma", mySigma_j) |
| 162 |
|
| 163 |
ljMixed(i,j)%sigma = & |
| 164 |
calcLJMix("sigma",mySigma_i, & |
| 165 |
mySigma_j) |
| 166 |
|
| 167 |
ljMixed(i,j)%sigma6 = & |
| 168 |
(ljMixed(i,j)%sigma)**6 |
| 169 |
|
| 170 |
|
| 171 |
ljMixed(i,j)%tp6 = ljMixed(i,j)%sigma6/rcut6 |
| 172 |
|
| 173 |
ljMixed(i,j)%tp12 = (ljMixed(i,j)%tp6) ** 2 |
| 174 |
|
| 175 |
|
| 176 |
ljMixed(i,j)%epsilon = & |
| 177 |
calcLJMix("epsilon",myEpsilon_i, & |
| 178 |
myEpsilon_j) |
| 179 |
|
| 180 |
ljMixed(i,j)%delta = -4.0_DP * ljMixed(i,j)%epsilon * & |
| 181 |
(ljMixed(i,j)%tp12 - ljMixed(i,j)%tp6) |
| 182 |
|
| 183 |
|
| 184 |
ljMixed(j,i)%sigma = ljMixed(i,j)%sigma |
| 185 |
ljMixed(j,i)%sigma6 = ljMixed(i,j)%sigma6 |
| 186 |
ljMixed(j,i)%tp6 = ljMixed(i,j)%tp6 |
| 187 |
ljMixed(j,i)%tp12 = ljMixed(i,j)%tp12 |
| 188 |
ljMixed(j,i)%epsilon = ljMixed(i,j)%epsilon |
| 189 |
ljMixed(j,i)%delta = ljMixed(i,j)%delta |
| 190 |
|
| 191 |
end do |
| 192 |
end do |
| 193 |
|
| 194 |
end subroutine createMixingList |
| 195 |
|
| 196 |
subroutine do_lj_pair(atom1, atom2, d, rij, r2, sw, vpair, fpair, & |
| 197 |
pot, f, do_pot) |
| 198 |
|
| 199 |
integer, intent(in) :: atom1, atom2 |
| 200 |
real( kind = dp ), intent(in) :: rij, r2 |
| 201 |
real( kind = dp ) :: pot, sw, vpair |
| 202 |
real( kind = dp ), dimension(3,nLocal) :: f |
| 203 |
real( kind = dp ), intent(in), dimension(3) :: d |
| 204 |
real( kind = dp ), intent(inout), dimension(3) :: fpair |
| 205 |
logical, intent(in) :: do_pot |
| 206 |
|
| 207 |
! local Variables |
| 208 |
real( kind = dp ) :: drdx, drdy, drdz |
| 209 |
real( kind = dp ) :: fx, fy, fz |
| 210 |
real( kind = dp ) :: pot_temp, dudr |
| 211 |
real( kind = dp ) :: sigma6 |
| 212 |
real( kind = dp ) :: epsilon |
| 213 |
real( kind = dp ) :: r6 |
| 214 |
real( kind = dp ) :: t6 |
| 215 |
real( kind = dp ) :: t12 |
| 216 |
real( kind = dp ) :: delta |
| 217 |
integer :: id1, id2 |
| 218 |
|
| 219 |
! Look up the correct parameters in the mixing matrix |
| 220 |
#ifdef IS_MPI |
| 221 |
sigma6 = ljMixed(atid_Row(atom1),atid_Col(atom2))%sigma6 |
| 222 |
epsilon = ljMixed(atid_Row(atom1),atid_Col(atom2))%epsilon |
| 223 |
delta = ljMixed(atid_Row(atom1),atid_Col(atom2))%delta |
| 224 |
#else |
| 225 |
sigma6 = ljMixed(atid(atom1),atid(atom2))%sigma6 |
| 226 |
epsilon = ljMixed(atid(atom1),atid(atom2))%epsilon |
| 227 |
delta = ljMixed(atid(atom1),atid(atom2))%delta |
| 228 |
#endif |
| 229 |
|
| 230 |
r6 = r2 * r2 * r2 |
| 231 |
|
| 232 |
t6 = sigma6/ r6 |
| 233 |
t12 = t6 * t6 |
| 234 |
|
| 235 |
pot_temp = 4.0E0_DP * epsilon * (t12 - t6) |
| 236 |
if (LJ_do_shift) then |
| 237 |
pot_temp = pot_temp + delta |
| 238 |
endif |
| 239 |
|
| 240 |
vpair = vpair + pot_temp |
| 241 |
|
| 242 |
dudr = sw * 24.0E0_DP * epsilon * (t6 - 2.0E0_DP*t12) / rij |
| 243 |
|
| 244 |
drdx = d(1) / rij |
| 245 |
drdy = d(2) / rij |
| 246 |
drdz = d(3) / rij |
| 247 |
|
| 248 |
fx = dudr * drdx |
| 249 |
fy = dudr * drdy |
| 250 |
fz = dudr * drdz |
| 251 |
|
| 252 |
|
| 253 |
#ifdef IS_MPI |
| 254 |
if (do_pot) then |
| 255 |
pot_Row(atom1) = pot_Row(atom1) + sw*pot_temp*0.5 |
| 256 |
pot_Col(atom2) = pot_Col(atom2) + sw*pot_temp*0.5 |
| 257 |
endif |
| 258 |
|
| 259 |
f_Row(1,atom1) = f_Row(1,atom1) + fx |
| 260 |
f_Row(2,atom1) = f_Row(2,atom1) + fy |
| 261 |
f_Row(3,atom1) = f_Row(3,atom1) + fz |
| 262 |
|
| 263 |
f_Col(1,atom2) = f_Col(1,atom2) - fx |
| 264 |
f_Col(2,atom2) = f_Col(2,atom2) - fy |
| 265 |
f_Col(3,atom2) = f_Col(3,atom2) - fz |
| 266 |
|
| 267 |
#else |
| 268 |
if (do_pot) pot = pot + sw*pot_temp |
| 269 |
|
| 270 |
f(1,atom1) = f(1,atom1) + fx |
| 271 |
f(2,atom1) = f(2,atom1) + fy |
| 272 |
f(3,atom1) = f(3,atom1) + fz |
| 273 |
|
| 274 |
f(1,atom2) = f(1,atom2) - fx |
| 275 |
f(2,atom2) = f(2,atom2) - fy |
| 276 |
f(3,atom2) = f(3,atom2) - fz |
| 277 |
#endif |
| 278 |
|
| 279 |
#ifdef IS_MPI |
| 280 |
id1 = AtomRowToGlobal(atom1) |
| 281 |
id2 = AtomColToGlobal(atom2) |
| 282 |
#else |
| 283 |
id1 = atom1 |
| 284 |
id2 = atom2 |
| 285 |
#endif |
| 286 |
|
| 287 |
if (molMembershipList(id1) .ne. molMembershipList(id2)) then |
| 288 |
|
| 289 |
fpair(1) = fpair(1) + fx |
| 290 |
fpair(2) = fpair(2) + fy |
| 291 |
fpair(3) = fpair(3) + fz |
| 292 |
|
| 293 |
endif |
| 294 |
|
| 295 |
return |
| 296 |
|
| 297 |
end subroutine do_lj_pair |
| 298 |
|
| 299 |
|
| 300 |
!! Calculates the mixing for sigma or epslon |
| 301 |
|
| 302 |
function calcLJMix(thisParam,param1,param2,status) result(myMixParam) |
| 303 |
character(len=*) :: thisParam |
| 304 |
real(kind = dp) :: param1 |
| 305 |
real(kind = dp) :: param2 |
| 306 |
real(kind = dp ) :: myMixParam |
| 307 |
|
| 308 |
integer, optional :: status |
| 309 |
|
| 310 |
myMixParam = 0.0_dp |
| 311 |
|
| 312 |
if (present(status)) status = 0 |
| 313 |
select case (LJ_Mixing_Policy) |
| 314 |
case (1) |
| 315 |
select case (thisParam) |
| 316 |
case ("sigma") |
| 317 |
myMixParam = 0.5_dp * (param1 + param2) |
| 318 |
case ("epsilon") |
| 319 |
myMixParam = sqrt(param1 * param2) |
| 320 |
case default |
| 321 |
status = -1 |
| 322 |
end select |
| 323 |
case default |
| 324 |
status = -1 |
| 325 |
end select |
| 326 |
end function calcLJMix |
| 327 |
|
| 328 |
end module lj |
