| 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 1.6 2003-03-12 15:39:01 gezelter Exp $, $Date: 2003-03-12 15:39:01 $, $Name: not supported by cvs2svn $, $Revision: 1.6 $ |
| 6 |
|
| 7 |
module lj |
| 8 |
use simulation |
| 9 |
use definitions |
| 10 |
use forceGlobals |
| 11 |
use atype_typedefs |
| 12 |
use vector_class |
| 13 |
#ifdef IS_MPI |
| 14 |
use mpiSimulation |
| 15 |
#endif |
| 16 |
implicit none |
| 17 |
PRIVATE |
| 18 |
|
| 19 |
!! Logical has lj force field module been initialized? |
| 20 |
logical, save :: isljFFinit = .false. |
| 21 |
|
| 22 |
!! Public methods and data |
| 23 |
public :: init_ljFF |
| 24 |
public :: do_lj_pair |
| 25 |
|
| 26 |
type :: lj_mixed_params |
| 27 |
!! Lennard-Jones epsilon |
| 28 |
real ( kind = dp ) :: epsilon = 0.0_dp |
| 29 |
!! Lennard-Jones Sigma |
| 30 |
real ( kind = dp ) :: sigma = 0.0_dp |
| 31 |
!! Lennard-Jones Sigma to sixth |
| 32 |
real ( kind = dp ) :: sigma6 = 0.0_dp |
| 33 |
!! |
| 34 |
real ( kind = dp ) :: tp6 |
| 35 |
real ( kind = dp ) :: tp12 |
| 36 |
|
| 37 |
real ( kind = dp ) :: delta = 0.0_dp |
| 38 |
|
| 39 |
end type lj_mixed_params |
| 40 |
|
| 41 |
type (lj_mixed_params), dimension(:,:), pointer :: ljMixed |
| 42 |
|
| 43 |
contains |
| 44 |
|
| 45 |
subroutine init_ljFF(status) |
| 46 |
integer, intent(out) :: status |
| 47 |
integer :: myStatus |
| 48 |
|
| 49 |
status = 0 |
| 50 |
call createMixingList(myStatus) |
| 51 |
if (myStatus /= 0) then |
| 52 |
status = -1 |
| 53 |
return |
| 54 |
end if |
| 55 |
|
| 56 |
end subroutine init_ljFF |
| 57 |
|
| 58 |
subroutine createMixingList(status) |
| 59 |
integer :: nAtypes |
| 60 |
integer :: status |
| 61 |
integer :: i |
| 62 |
integer :: j |
| 63 |
real ( kind = dp ) :: mySigma_i,mySigma_j |
| 64 |
real ( kind = dp ) :: myEpsilon_i,myEpsilon_j |
| 65 |
real ( kind = dp ) :: rcut, rcut6 |
| 66 |
status = 0 |
| 67 |
|
| 68 |
nAtypes = getSize(atypes) |
| 69 |
if (nAtypes == 0) then |
| 70 |
status = -1 |
| 71 |
return |
| 72 |
end if |
| 73 |
|
| 74 |
if (.not. associated(ljMixed)) then |
| 75 |
allocate(ljMixed(nAtypes, nAtypes)) |
| 76 |
else |
| 77 |
status = -1 |
| 78 |
return |
| 79 |
end if |
| 80 |
call getRcut(rcut, rcut6=rcut6) |
| 81 |
do i = 1, nAtypes |
| 82 |
|
| 83 |
call getElementProperty(atypes,i,"lj_epsilon",myEpsilon_i) |
| 84 |
call getElementProperty(atypes,i,"lj_sigma", mySigma_i) |
| 85 |
! do self mixing rule |
| 86 |
ljMixed(i,i)%sigma = mySigma_i |
| 87 |
|
| 88 |
ljMixed(i,i)%sigma6 = (ljMixed(i,i)%sigma) ** 6 |
| 89 |
ljMixed(i,i)%tp6 = ljMixed(i,i)%sigma6/rcut6 |
| 90 |
|
| 91 |
ljMixed(i,i)%tp12 = (ljMixed(i,i)%tp6) ** 2 |
| 92 |
|
| 93 |
ljMixed(i,i)%epsilon = myEpsilon_i |
| 94 |
|
| 95 |
ljMixed(i,i)%delta = -4.0_DP * ljMixed(i,i)%epsilon * & |
| 96 |
(ljMixed(i,i)%tp12 - ljMixed(i,i)%tp6) |
| 97 |
|
| 98 |
do j = i + 1, nAtypes |
| 99 |
call getElementProperty(atypes,j,"lj_epsilon",myEpsilon_j) |
| 100 |
call getElementProperty(atypes,j,"lj_sigma", mySigma_j) |
| 101 |
|
| 102 |
ljMixed(i,j)%sigma = & |
| 103 |
calcLJMix("sigma",mySigma_i, & |
| 104 |
mySigma_j) |
| 105 |
|
| 106 |
ljMixed(i,j)%sigma6 = & |
| 107 |
(ljMixed(i,j)%sigma)**6 |
| 108 |
|
| 109 |
|
| 110 |
ljMixed(i,j)%tp6 = ljMixed(i,j)%sigma6/rcut6 |
| 111 |
|
| 112 |
ljMixed(i,j)%tp12 = (ljMixed(i,j)%tp6) ** 2 |
| 113 |
|
| 114 |
|
| 115 |
ljMixed(i,j)%epsilon = & |
| 116 |
calcLJMix("epsilon",myEpsilon_i, & |
| 117 |
myEpsilon_j) |
| 118 |
|
| 119 |
ljMixed(i,j)%delta = -4.0_DP * ljMixed(i,j)%epsilon * & |
| 120 |
(ljMixed(i,j)%tp12 - ljMixed(i,j)%tp6) |
| 121 |
|
| 122 |
|
| 123 |
ljMixed(j,i)%sigma = ljMixed(i,j)%sigma |
| 124 |
ljMixed(j,i)%sigma6 = ljMixed(i,j)%sigma6 |
| 125 |
ljMixed(j,i)%tp6 = ljMixed(i,j)%tp6 |
| 126 |
ljMixed(j,i)%tp12 = ljMixed(i,j)%tp12 |
| 127 |
ljMixed(j,i)%epsilon = ljMixed(i,j)%epsilon |
| 128 |
ljMixed(j,i)%delta = ljMixed(i,j)%delta |
| 129 |
|
| 130 |
end do |
| 131 |
end do |
| 132 |
|
| 133 |
end subroutine createMixingList |
| 134 |
|
| 135 |
|
| 136 |
subroutine do_lj_pair(atom1, atom2, d, rij, r2, pot, f) |
| 137 |
|
| 138 |
integer, intent(in) :: atom1, atom2 |
| 139 |
real( kind = dp ), intent(in) :: rij, r2 |
| 140 |
real( kind = dp ) :: pot |
| 141 |
real( kind = dp ), dimension(3, getNlocal()) :: f |
| 142 |
real( kind = dp ), intent(in), dimension(3) :: d |
| 143 |
|
| 144 |
! local Variables |
| 145 |
real( kind = dp ) :: drdx, drdy, drdz |
| 146 |
real( kind = dp ) :: fx, fy, fz |
| 147 |
real( kind = dp ) :: pot_temp, dudr |
| 148 |
real( kind = dp ) :: sigma6 |
| 149 |
real( kind = dp ) :: epsilon |
| 150 |
real( kind = dp ) :: rcut |
| 151 |
real( kind = dp ) :: r6 |
| 152 |
real( kind = dp ) :: t6 |
| 153 |
real( kind = dp ) :: t12 |
| 154 |
real( kind = dp ) :: delta |
| 155 |
|
| 156 |
! Look up the correct parameters in the mixing matrix |
| 157 |
#ifdef IS_MPI |
| 158 |
sigma6 = ljMixed(atid_Row(atom1),atid_Col(atom2))%sigma6 |
| 159 |
epsilon = ljMixed(atid_Row(atom1),atid_Col(atom2))%epsilon |
| 160 |
delta = ljMixed(atid_Row(atom1),atid_Col(atom2))%delta |
| 161 |
#else |
| 162 |
sigma6 = ljMixed(atid(atom1),atid(atom2))%sigma6 |
| 163 |
epsilon = ljMixed(atid(atom1),atid(atom2))%epsilon |
| 164 |
delta = ljMixed(atid(atom1),atid(atom2))%delta |
| 165 |
#endif |
| 166 |
|
| 167 |
call getRcut(rcut) |
| 168 |
|
| 169 |
r6 = r2 * r2 * r2 |
| 170 |
|
| 171 |
t6 = sigma6/ r6 |
| 172 |
t12 = t6 * t6 |
| 173 |
|
| 174 |
if (rij.le.rcut) then |
| 175 |
|
| 176 |
pot_temp = 4.0E0_DP * epsilon * (t12 - t6) + delta |
| 177 |
|
| 178 |
dudr = 24.0E0_DP * epsilon * (t6 - 2.0E0_DP*t12) / rij |
| 179 |
|
| 180 |
drdx = -d(1) / rij |
| 181 |
drdy = -d(2) / rij |
| 182 |
drdz = -d(3) / rij |
| 183 |
|
| 184 |
fx = dudr * drdx |
| 185 |
fy = dudr * drdy |
| 186 |
fz = dudr * drdz |
| 187 |
|
| 188 |
#ifdef IS_MPI |
| 189 |
pot_Row(atom1) = pot_Row(atom1) + pot_temp*0.5 |
| 190 |
pot_Col(atom2) = pot_Col(atom2) + pot_temp*0.5 |
| 191 |
|
| 192 |
f_Row(1,atom1) = f_Row(1,atom1) + fx |
| 193 |
f_Row(2,atom1) = f_Row(2,atom1) + fy |
| 194 |
f_Row(3,atom1) = f_Row(3,atom1) + fz |
| 195 |
|
| 196 |
f_Col(1,atom2) = f_Col(1,atom2) - fx |
| 197 |
f_Col(2,atom2) = f_Col(2,atom2) - fy |
| 198 |
f_Col(3,atom2) = f_Col(3,atom2) - fz |
| 199 |
|
| 200 |
#else |
| 201 |
pot = pot + pot_temp |
| 202 |
|
| 203 |
f(1,atom1) = f(1,atom1) + fx |
| 204 |
f(2,atom1) = f(2,atom1) + fy |
| 205 |
f(3,atom1) = f(3,atom1) + fz |
| 206 |
|
| 207 |
f(1,atom2) = f(1,atom2) - fx |
| 208 |
f(2,atom2) = f(2,atom2) - fy |
| 209 |
f(3,atom2) = f(3,atom2) - fz |
| 210 |
#endif |
| 211 |
|
| 212 |
if (doStress()) then |
| 213 |
tau_Temp(1) = tau_Temp(1) + fx * d(1) |
| 214 |
tau_Temp(2) = tau_Temp(2) + fx * d(2) |
| 215 |
tau_Temp(3) = tau_Temp(3) + fx * d(3) |
| 216 |
tau_Temp(4) = tau_Temp(4) + fy * d(1) |
| 217 |
tau_Temp(5) = tau_Temp(5) + fy * d(2) |
| 218 |
tau_Temp(6) = tau_Temp(6) + fy * d(3) |
| 219 |
tau_Temp(7) = tau_Temp(7) + fz * d(1) |
| 220 |
tau_Temp(8) = tau_Temp(8) + fz * d(2) |
| 221 |
tau_Temp(9) = tau_Temp(9) + fz * d(3) |
| 222 |
virial_Temp = virial_Temp + (tau_Temp(1) + tau_Temp(5) + tau_Temp(9)) |
| 223 |
endif |
| 224 |
|
| 225 |
endif |
| 226 |
return |
| 227 |
end subroutine do_lj_pair |
| 228 |
|
| 229 |
|
| 230 |
!! Calculates the mixing for sigma or epslon based on character |
| 231 |
!! string for initialzition of mixing array. |
| 232 |
function calcLJMix(thisParam,param1,param2,status) result(myMixParam) |
| 233 |
character(len=*) :: thisParam |
| 234 |
real(kind = dp) :: param1 |
| 235 |
real(kind = dp) :: param2 |
| 236 |
real(kind = dp ) :: myMixParam |
| 237 |
character(len = getStringLen()) :: thisMixingRule |
| 238 |
integer, optional :: status |
| 239 |
|
| 240 |
!! get the mixing rules from the simulation |
| 241 |
thisMixingRule = returnMixingRules() |
| 242 |
myMixParam = 0.0_dp |
| 243 |
|
| 244 |
if (present(status)) status = 0 |
| 245 |
select case (thisMixingRule) |
| 246 |
case ("standard") |
| 247 |
select case (thisParam) |
| 248 |
case ("sigma") |
| 249 |
myMixParam = 0.5_dp * (param1 + param2) |
| 250 |
case ("epsilon") |
| 251 |
myMixParam = sqrt(param1 * param2) |
| 252 |
case default |
| 253 |
status = -1 |
| 254 |
end select |
| 255 |
case("LJglass") |
| 256 |
case default |
| 257 |
status = -1 |
| 258 |
end select |
| 259 |
end function calcLJMix |
| 260 |
|
| 261 |
end module lj |
