| 1 |
module lj_ff |
| 2 |
use simulation |
| 3 |
use definitions, ONLY : dp, ndim |
| 4 |
#ifdef IS_MPI |
| 5 |
use mpiSimulation |
| 6 |
#endif |
| 7 |
implicit none |
| 8 |
PRIVATE |
| 9 |
|
| 10 |
!! Number of lj_atypes in lj_atype_list |
| 11 |
integer, save :: n_lj_atypes = 0 |
| 12 |
|
| 13 |
!! Starting Size for ljMixed Array |
| 14 |
integer, parameter :: ljMixed_blocksize = 10 |
| 15 |
|
| 16 |
type, public :: lj_atype |
| 17 |
private |
| 18 |
sequence |
| 19 |
!! Unique number for place in linked list |
| 20 |
integer :: atype_number = 0 |
| 21 |
!! Unique indentifier number (ie atomic no, etc) |
| 22 |
integer :: atype_ident = 0 |
| 23 |
!! Mass of Particle |
| 24 |
real ( kind = dp ) :: mass = 0.0_dp |
| 25 |
!! Lennard-Jones epslon |
| 26 |
real ( kind = dp ) :: epslon = 0.0_dp |
| 27 |
!! Lennard-Jones Sigma |
| 28 |
real ( kind = dp ) :: sigma = 0.0_dp |
| 29 |
!! Lennard-Jones Sigma Squared |
| 30 |
real ( kind = dp ) :: sigma2 = 0.0_dp |
| 31 |
!! Lennard-Jones Sigma to sixth |
| 32 |
real ( kind = dp ) :: sigma6 = 0.0_dp |
| 33 |
!! Pointer for linked list creation |
| 34 |
type (lj_atype), pointer :: next => null() |
| 35 |
end type lj_atype |
| 36 |
|
| 37 |
!! Pointer type for atype ident array |
| 38 |
type, public :: lj_atypePtr |
| 39 |
type (lj_atype), pointer :: this => null() |
| 40 |
end type lj_atypePtr |
| 41 |
|
| 42 |
!! Global list of lj atypes in simulation |
| 43 |
type (lj_atype), pointer :: lj_atype_list => null() |
| 44 |
!! LJ mixing array |
| 45 |
type (lj_atype), dimension(:,:), allocatable, pointer :: ljMixed =>null() |
| 46 |
!! identity pointer list for force loop. |
| 47 |
type (lj_atypePtr), dimension(:), allocatable :: identPtrList |
| 48 |
|
| 49 |
|
| 50 |
!! Neighbor list and commom arrays |
| 51 |
integer, allocatable, dimension(:) :: point |
| 52 |
integer, allocatable, dimension(:) :: list |
| 53 |
|
| 54 |
#ifdef IS_MPI |
| 55 |
! Universal routines: All types of force calculations will need these arrays |
| 56 |
! Arrays specific to a type of force calculation should be declared in that module. |
| 57 |
real( kind = dp ), allocatable, dimension(:,:) :: qRow |
| 58 |
real( kind = dp ), allocatable, dimension(:,:) :: qColumn |
| 59 |
|
| 60 |
real( kind = dp ), allocatable, dimension(:,:) :: fRow |
| 61 |
real( kind = dp ), allocatable, dimension(:,:) :: fColumn |
| 62 |
#endif |
| 63 |
|
| 64 |
|
| 65 |
|
| 66 |
|
| 67 |
|
| 68 |
|
| 69 |
!! Public methods and data |
| 70 |
public :: new_lj_atype |
| 71 |
public :: do_lj_ff |
| 72 |
public :: getLjPot |
| 73 |
|
| 74 |
|
| 75 |
|
| 76 |
|
| 77 |
|
| 78 |
contains |
| 79 |
|
| 80 |
subroutine new_lj_atype(ident,mass,epslon,sigma,status) |
| 81 |
real( kind = dp ), intent(in) :: mass |
| 82 |
real( kind = dp ), intent(in) :: epslon |
| 83 |
real( kind = dp ), intent(in) :: sigma |
| 84 |
integer, intent(in) :: ident |
| 85 |
integer, intent(out) :: status |
| 86 |
|
| 87 |
type (lj_atype), pointer :: this_lj_atype |
| 88 |
type (lj_atype), pointer :: lj_atype_ptr |
| 89 |
|
| 90 |
type (lj_atype), allocatable, dimension(:,:), pointer :: thisMix |
| 91 |
type (lj_atype), allocatable, dimension(:,:), pointer :: oldMix |
| 92 |
integer :: alloc_error |
| 93 |
integer :: atype_counter = 0 |
| 94 |
integer :: alloc_size |
| 95 |
|
| 96 |
status = 0 |
| 97 |
|
| 98 |
|
| 99 |
|
| 100 |
! allocate a new atype |
| 101 |
allocate(this_lj_atype,stat=alloc_error) |
| 102 |
if (alloc_error /= 0 ) then |
| 103 |
status = -1 |
| 104 |
return |
| 105 |
end if |
| 106 |
|
| 107 |
! assign our new lj_atype information |
| 108 |
this_lj_atype%mass = mass |
| 109 |
this_lj_atype%epslon = epslon |
| 110 |
this_lj_atype%sigma = sigma |
| 111 |
this_lj_atype%sigma2 = sigma * sigma |
| 112 |
this_lj_atype%sigma6 = this_lj_atype%sigma2 * this_lj_atype%sigma2 & |
| 113 |
* this_lj_atype%sigma2 |
| 114 |
! assume that this atype will be successfully added |
| 115 |
this_lj_atype%atype_ident = ident |
| 116 |
this_lj_atype%number = n_lj_atypes + 1 |
| 117 |
|
| 118 |
|
| 119 |
! First time through allocate a array of size ljMixed_blocksize |
| 120 |
if(.not. associated(ljMixed)) then |
| 121 |
allocate(thisMix(ljMixed_blocksize,ljMixed_blocksize)) |
| 122 |
if (alloc_error /= 0 ) then |
| 123 |
status = -1 |
| 124 |
return |
| 125 |
end if |
| 126 |
ljMixed => thisMix |
| 127 |
! If we have outgrown ljMixed_blocksize, allocate a new matrix twice the size and |
| 128 |
! point ljMix at the new matrix. |
| 129 |
else if( (n_lj_atypes + 1) > size(ljMixed)) then |
| 130 |
alloc_size = 2*size(ljMix) |
| 131 |
allocate(thisMix(alloc_size,alloc_size)) |
| 132 |
if (alloc_error /= 0 ) then |
| 133 |
status = -1 |
| 134 |
return |
| 135 |
end if |
| 136 |
! point oldMix at old ljMixed array |
| 137 |
oldMix => ljMixed |
| 138 |
! Copy oldMix into new Mixed array |
| 139 |
thisMix = oldMix |
| 140 |
! Point ljMixed at new array |
| 141 |
ljMixed => thisMix |
| 142 |
! Free old array so we don't have a memory leak |
| 143 |
deallocate(oldMix) |
| 144 |
endif |
| 145 |
|
| 146 |
|
| 147 |
|
| 148 |
|
| 149 |
|
| 150 |
! Find bottom of atype master list |
| 151 |
! if lj_atype_list is null then we are at the top of the list. |
| 152 |
if (.not. associated(lj_atype_list)) then |
| 153 |
lj_atype_ptr => this_lj_atype |
| 154 |
atype_counter = 1 |
| 155 |
|
| 156 |
else ! we need to find the bottom of the list to insert new atype |
| 157 |
lj_atype_ptr => lj_atype_list%next |
| 158 |
atype_counter = 1 |
| 159 |
find_end: do |
| 160 |
if (.not. associated(lj_atype_ptr%next)) then |
| 161 |
exit find_end |
| 162 |
end if |
| 163 |
! Set up mixing for new atype and current atype in list |
| 164 |
ljMix(this_lj_atype%atype_number,lj_atype_ptr%atype_number)%sigma = & |
| 165 |
calcLJMix("sigma",this_lj_atype%sigma, & |
| 166 |
lj_atype_prt%sigma) |
| 167 |
|
| 168 |
ljMix(this_lj_atype%atype_number,lj_atype_ptr%atype_number)%sigma2 = & |
| 169 |
ljMix(this_lj_atype%atype_number,lj_atype_ptr%atype_number)%sigma & |
| 170 |
* ljMix(this_lj_atype%atype_number,lj_atype_ptr%atype_number)%sigma |
| 171 |
|
| 172 |
ljMix(this_lj_atype%atype_number,lj_atype_ptr%atype_number)%sigma6 = & |
| 173 |
ljMix(this_lj_atype%atype_number,lj_atype_ptr%atype_number)%sigma2 & |
| 174 |
* ljMix(this_lj_atype%atype_number,lj_atype_ptr%atype_number)%sigma2 & |
| 175 |
* ljMix(this_lj_atype%atype_number,lj_atype_ptr%atype_number)%sigma2 |
| 176 |
|
| 177 |
ljMix(this_lj_atype%atype_number,lj_atype_ptr%atype_number)%epslon = & |
| 178 |
calcLJMix("epslon",this_lj_atype%epslon, & |
| 179 |
lj_atype_prt%epslon) |
| 180 |
|
| 181 |
! Advance to next pointer |
| 182 |
lj_atype_ptr => lj_atype_ptr%next |
| 183 |
atype_counter = atype_counter + 1 |
| 184 |
|
| 185 |
end do find_end |
| 186 |
end if |
| 187 |
|
| 188 |
|
| 189 |
|
| 190 |
|
| 191 |
! Insert new atype at end of list |
| 192 |
lj_atype_ptr => this_lj_atype |
| 193 |
! Increment number of atypes |
| 194 |
|
| 195 |
n_lj_atypes = n_lj_atypes + 1 |
| 196 |
|
| 197 |
! Set up self mixing |
| 198 |
|
| 199 |
ljMix(n_lj_atypes,n_lj_atypes)%sigma = this_lj_atype%sigma |
| 200 |
|
| 201 |
ljMix(n_lj_atypes,n_lj_atypes)%sigma2 = ljMix(n_lj_atypes,n_lj_atypes)%sigma & |
| 202 |
* ljMix(n_lj_atypes,n_lj_atypes)%sigma |
| 203 |
|
| 204 |
ljMix(n_lj_atypes,n_lj_atypes)%sigma6 = ljMix(n_lj_atypes,n_lj_atypes)%sigma2 & |
| 205 |
* ljMix(n_lj_atypes,n_lj_atypes)%sigma2 & |
| 206 |
* ljMix(n_lj_atypes,n_lj_atypes)%sigma2 |
| 207 |
|
| 208 |
ljMix(n_lj_atypes,n_lj_atypes)%epslon = this_lj_atype%epslon |
| 209 |
|
| 210 |
|
| 211 |
end subroutine new_lj_atype |
| 212 |
|
| 213 |
|
| 214 |
subroutine init_ljFF() |
| 215 |
|
| 216 |
|
| 217 |
#ifdef IS_MPI |
| 218 |
|
| 219 |
|
| 220 |
|
| 221 |
#endif |
| 222 |
|
| 223 |
end subroutine init_ljFF |
| 224 |
|
| 225 |
!! Takes an ident array and creates an atype pointer list |
| 226 |
!! based on those identities |
| 227 |
subroutine new_ljatypePtrList(mysize,ident,PtrList,status) |
| 228 |
integer, intent(in) :: mysize |
| 229 |
integer, intent(in) :: ident |
| 230 |
integer, optional :: status |
| 231 |
type(lj_atypePtr), dimension(:) :: PtrList |
| 232 |
|
| 233 |
integer :: thisIdent |
| 234 |
integer :: i |
| 235 |
integer :: alloc_error |
| 236 |
type (lj_atype), pointer :: tmpPtr |
| 237 |
|
| 238 |
if (present(status)) status = 0 |
| 239 |
|
| 240 |
! First time through, allocate list |
| 241 |
if (.not.(allocated)) then |
| 242 |
allocate(PtrList(mysize)) |
| 243 |
else |
| 244 |
! We want to creat a new ident list so free old list |
| 245 |
deallocate(PrtList) |
| 246 |
allocate(PtrList(mysize)) |
| 247 |
endif |
| 248 |
|
| 249 |
! Match pointer list |
| 250 |
do i = 1, mysize |
| 251 |
thisIdent = ident(i) |
| 252 |
call getLJatype(thisIdent,tmpPtr) |
| 253 |
|
| 254 |
if (.not. associated(tmpPtr)) then |
| 255 |
status = -1 |
| 256 |
return |
| 257 |
endif |
| 258 |
|
| 259 |
PtrList(i)%this => tmpPtr |
| 260 |
end do |
| 261 |
|
| 262 |
end subroutine new_ljatypePtrList |
| 263 |
|
| 264 |
!! Finds a lj_atype based upon numerical ident |
| 265 |
!! returns a null pointer if error |
| 266 |
subroutine getLJatype(ident,ljAtypePtr) |
| 267 |
integer, intent(in) :: ident |
| 268 |
type (lj_atype), intent(out),pointer :: ljAtypePtr => null() |
| 269 |
|
| 270 |
type (lj_atype), pointer :: tmplj_atype_ptr => null() |
| 271 |
|
| 272 |
if(.not. associated(lj_atype_list)) return |
| 273 |
|
| 274 |
! Point at head of list. |
| 275 |
tmplj_atype_ptr => lj_atype_list |
| 276 |
find_ident: do |
| 277 |
if (.not.associated(tmplj_atype_ptr)) then |
| 278 |
exit find_ident |
| 279 |
else if( lj_atype_ptr%atype_ident == ident) |
| 280 |
ljAtypePtr => tmplj_atype_ptr |
| 281 |
exit find_ident |
| 282 |
endif |
| 283 |
tmplj_atype_ptr => tmplj_atype_ptr%next |
| 284 |
end do find_ident |
| 285 |
|
| 286 |
end subroutine getLJatype |
| 287 |
|
| 288 |
|
| 289 |
! FORCE routine |
| 290 |
!-------------------------------------------------------------> |
| 291 |
subroutine do_lj_ff(q,f,potE,do_pot) |
| 292 |
real ( kind = dp ), dimension(ndim,) :: q |
| 293 |
real ( kind = dp ), dimension(ndim,nLRparticles) :: f |
| 294 |
real ( kind = dp ) :: potE |
| 295 |
logical :: do_pot |
| 296 |
#ifdef MPI |
| 297 |
real( kind = DP ), dimension(3,ncol) :: efr |
| 298 |
real( kind = DP ) :: pot_local |
| 299 |
#else |
| 300 |
! real( kind = DP ), dimension(3,natoms) :: efr |
| 301 |
#endif |
| 302 |
|
| 303 |
real( kind = DP ) :: pe |
| 304 |
logical, :: update_nlist |
| 305 |
|
| 306 |
|
| 307 |
integer :: i, j, jbeg, jend, jnab, idim, jdim, idim2, jdim2, dim, dim2 |
| 308 |
integer :: nlist |
| 309 |
integer :: j_start |
| 310 |
integer :: tag_i,tag_j |
| 311 |
real( kind = DP ) :: r, pot, ftmp, dudr, d2, drdx1, kt1, kt2, kt3, ktmp |
| 312 |
real( kind = DP ) :: rxi, ryi, rzi, rxij, ryij, rzij, rijsq |
| 313 |
|
| 314 |
integer :: nrow |
| 315 |
integer :: ncol |
| 316 |
|
| 317 |
|
| 318 |
|
| 319 |
#ifndef IS_MPI |
| 320 |
nrow = natoms - 1 |
| 321 |
ncol = natoms |
| 322 |
#else |
| 323 |
j_start = 1 |
| 324 |
#endif |
| 325 |
|
| 326 |
call check(update_nlist) |
| 327 |
|
| 328 |
#ifndef IS_MPI |
| 329 |
nloops = nloops + 1 |
| 330 |
pot = 0.0E0_DP |
| 331 |
f = 0.0E0_DP |
| 332 |
e = 0.0E0_DP |
| 333 |
#else |
| 334 |
f_row = 0.0E0_DP |
| 335 |
f_col = 0.0E0_DP |
| 336 |
|
| 337 |
pot_local = 0.0E0_DP |
| 338 |
|
| 339 |
e_row = 0.0E0_DP |
| 340 |
e_col = 0.0E0_DP |
| 341 |
e_tmp = 0.0E0_DP |
| 342 |
#endif |
| 343 |
efr = 0.0E0_DP |
| 344 |
|
| 345 |
! communicate MPI positions |
| 346 |
#ifdef MPI |
| 347 |
call gather(q,q_row,plan_row3) |
| 348 |
call gather(q,q_col,plan_col3) |
| 349 |
#endif |
| 350 |
|
| 351 |
#ifndef MPI |
| 352 |
|
| 353 |
#endif |
| 354 |
|
| 355 |
if (update_nlist) then |
| 356 |
|
| 357 |
! save current configuration, contruct neighbor list, |
| 358 |
! and calculate forces |
| 359 |
call save_nlist() |
| 360 |
|
| 361 |
nlist = 0 |
| 362 |
|
| 363 |
|
| 364 |
|
| 365 |
do i = 1, nrow |
| 366 |
point(i) = nlist + 1 |
| 367 |
#ifdef MPI |
| 368 |
tag_i = tag_row(i) |
| 369 |
rxi = q_row(1,i) |
| 370 |
ryi = q_row(2,i) |
| 371 |
rzi = q_row(3,i) |
| 372 |
#else |
| 373 |
j_start = i + 1 |
| 374 |
rxi = q(1,i) |
| 375 |
ryi = q(2,i) |
| 376 |
rzi = q(3,i) |
| 377 |
#endif |
| 378 |
|
| 379 |
inner: do j = j_start, ncol |
| 380 |
#ifdef MPI |
| 381 |
tag_j = tag_col(j) |
| 382 |
if (newtons_thrd) then |
| 383 |
if (tag_i <= tag_j) then |
| 384 |
if (mod(tag_i + tag_j,2) == 0) cycle inner |
| 385 |
else |
| 386 |
if (mod(tag_i + tag_j,2) == 1) cycle inner |
| 387 |
endif |
| 388 |
endif |
| 389 |
|
| 390 |
rxij = wrap(rxi - q_col(1,j), 1) |
| 391 |
ryij = wrap(ryi - q_col(2,j), 2) |
| 392 |
rzij = wrap(rzi - q_col(3,j), 3) |
| 393 |
#else |
| 394 |
|
| 395 |
rxij = wrap(rxi - q(1,j), 1) |
| 396 |
ryij = wrap(ryi - q(2,j), 2) |
| 397 |
rzij = wrap(rzi - q(3,j), 3) |
| 398 |
|
| 399 |
#endif |
| 400 |
rijsq = rxij*rxij + ryij*ryij + rzij*rzij |
| 401 |
|
| 402 |
#ifdef MPI |
| 403 |
if (rijsq <= rlstsq .AND. & |
| 404 |
tag_j /= tag_i) then |
| 405 |
#else |
| 406 |
if (rijsq < rlstsq) then |
| 407 |
#endif |
| 408 |
|
| 409 |
nlist = nlist + 1 |
| 410 |
if (nlist > size(list)) then |
| 411 |
call info("FORCE_LJ","error size list smaller then nlist") |
| 412 |
write(msg,*) "nlist size(list)", nlist, size(list) |
| 413 |
call info("FORCE_LJ",msg) |
| 414 |
#ifdef MPI |
| 415 |
call mpi_abort(MPI_COMM_WORLD,mpi_err) |
| 416 |
#endif |
| 417 |
stop |
| 418 |
endif |
| 419 |
list(nlist) = j |
| 420 |
|
| 421 |
|
| 422 |
if (rijsq < rcutsq) then |
| 423 |
|
| 424 |
r = dsqrt(rijsq) |
| 425 |
|
| 426 |
call LJ_mix(r,pot,dudr,d2,i,j) |
| 427 |
|
| 428 |
#ifdef MPI |
| 429 |
e_row(i) = e_row(i) + pot*0.5 |
| 430 |
e_col(i) = e_col(i) + pot*0.5 |
| 431 |
#else |
| 432 |
pe = pe + pot |
| 433 |
#endif |
| 434 |
|
| 435 |
efr(1,j) = -rxij |
| 436 |
efr(2,j) = -ryij |
| 437 |
efr(3,j) = -rzij |
| 438 |
|
| 439 |
do dim = 1, 3 |
| 440 |
|
| 441 |
|
| 442 |
drdx1 = efr(dim,j) / r |
| 443 |
ftmp = dudr * drdx1 |
| 444 |
|
| 445 |
|
| 446 |
#ifdef MPI |
| 447 |
f_col(dim,j) = f_col(dim,j) - ftmp |
| 448 |
f_row(dim,i) = f_row(dim,i) + ftmp |
| 449 |
#else |
| 450 |
|
| 451 |
f(dim,j) = f(dim,j) - ftmp |
| 452 |
f(dim,i) = f(dim,i) + ftmp |
| 453 |
|
| 454 |
#endif |
| 455 |
enddo |
| 456 |
endif |
| 457 |
endif |
| 458 |
enddo inner |
| 459 |
enddo |
| 460 |
|
| 461 |
#ifdef MPI |
| 462 |
point(nrow + 1) = nlist + 1 |
| 463 |
#else |
| 464 |
point(natoms) = nlist + 1 |
| 465 |
#endif |
| 466 |
|
| 467 |
else |
| 468 |
|
| 469 |
! use the list to find the neighbors |
| 470 |
do i = 1, nrow |
| 471 |
JBEG = POINT(i) |
| 472 |
JEND = POINT(i+1) - 1 |
| 473 |
! check thiat molecule i has neighbors |
| 474 |
if (jbeg .le. jend) then |
| 475 |
#ifdef MPI |
| 476 |
rxi = q_row(1,i) |
| 477 |
ryi = q_row(2,i) |
| 478 |
rzi = q_row(3,i) |
| 479 |
#else |
| 480 |
rxi = q(1,i) |
| 481 |
ryi = q(2,i) |
| 482 |
rzi = q(3,i) |
| 483 |
#endif |
| 484 |
do jnab = jbeg, jend |
| 485 |
j = list(jnab) |
| 486 |
#ifdef MPI |
| 487 |
rxij = wrap(rxi - q_col(1,j), 1) |
| 488 |
ryij = wrap(ryi - q_col(2,j), 2) |
| 489 |
rzij = wrap(rzi - q_col(3,j), 3) |
| 490 |
#else |
| 491 |
rxij = wrap(rxi - q(1,j), 1) |
| 492 |
ryij = wrap(ryi - q(2,j), 2) |
| 493 |
rzij = wrap(rzi - q(3,j), 3) |
| 494 |
#endif |
| 495 |
rijsq = rxij*rxij + ryij*ryij + rzij*rzij |
| 496 |
|
| 497 |
if (rijsq < rcutsq) then |
| 498 |
|
| 499 |
r = dsqrt(rijsq) |
| 500 |
|
| 501 |
call LJ_mix(r,pot,dudr,d2,i,j) |
| 502 |
#ifdef MPI |
| 503 |
e_row(i) = e_row(i) + pot*0.5 |
| 504 |
e_col(i) = e_col(i) + pot*0.5 |
| 505 |
#else |
| 506 |
if (do_pot) pe = pe + pot |
| 507 |
#endif |
| 508 |
|
| 509 |
|
| 510 |
efr(1,j) = -rxij |
| 511 |
efr(2,j) = -ryij |
| 512 |
efr(3,j) = -rzij |
| 513 |
|
| 514 |
do dim = 1, 3 |
| 515 |
|
| 516 |
drdx1 = efr(dim,j) / r |
| 517 |
ftmp = dudr * drdx1 |
| 518 |
#ifdef MPI |
| 519 |
f_col(dim,j) = f_col(dim,j) - ftmp |
| 520 |
f_row(dim,i) = f_row(dim,i) + ftmp |
| 521 |
#else |
| 522 |
f(dim,j) = f(dim,j) - ftmp |
| 523 |
f(dim,i) = f(dim,i) + ftmp |
| 524 |
#endif |
| 525 |
enddo |
| 526 |
endif |
| 527 |
enddo |
| 528 |
endif |
| 529 |
enddo |
| 530 |
endif |
| 531 |
|
| 532 |
|
| 533 |
|
| 534 |
#ifdef MPI |
| 535 |
!!distribute forces |
| 536 |
call scatter(f_row,f,plan_row3) |
| 537 |
|
| 538 |
call scatter(f_col,f_tmp,plan_col3) |
| 539 |
do i = 1,nlocal |
| 540 |
do dim = 1,3 |
| 541 |
f(dim,i) = f(dim,i) + f_tmp(dim,i) |
| 542 |
end do |
| 543 |
end do |
| 544 |
|
| 545 |
|
| 546 |
|
| 547 |
if (do_pot) then |
| 548 |
! scatter/gather pot_row into the members of my column |
| 549 |
call scatter(e_row,e_tmp,plan_row) |
| 550 |
|
| 551 |
! scatter/gather pot_local into all other procs |
| 552 |
! add resultant to get total pot |
| 553 |
do i = 1, nlocal |
| 554 |
pot_local = pot_local + e_tmp(i) |
| 555 |
enddo |
| 556 |
if (newtons_thrd) then |
| 557 |
e_tmp = 0.0E0_DP |
| 558 |
call scatter(e_col,e_tmp,plan_col) |
| 559 |
do i = 1, nlocal |
| 560 |
pot_local = pot_local + e_tmp(i) |
| 561 |
enddo |
| 562 |
endif |
| 563 |
endif |
| 564 |
#endif |
| 565 |
|
| 566 |
|
| 567 |
|
| 568 |
|
| 569 |
end subroutine do_lj_ff |
| 570 |
|
| 571 |
!! Calculates the potential between two lj particles, optionally returns second |
| 572 |
!! derivatives. |
| 573 |
subroutine getLjPot(r,pot,dudr,atype1,atype2,d2,status) |
| 574 |
! arguments |
| 575 |
!! Length of vector between particles |
| 576 |
real( kind = dp ), intent(in) :: r |
| 577 |
!! Potential Energy |
| 578 |
real( kind = dp ), intent(out) :: pot |
| 579 |
!! Derivatve wrt postion |
| 580 |
real( kind = dp ), intent(out) :: dudr |
| 581 |
!! Second Derivative, optional, used mainly for normal mode calculations. |
| 582 |
real( kind = dp ), intent(out), optional :: d2 |
| 583 |
|
| 584 |
type (lj_atype), intent(in) :: atype1 |
| 585 |
type (lj_atype), intent(in) :: atype2 |
| 586 |
|
| 587 |
integer, intent(out), optional :: status |
| 588 |
|
| 589 |
! local Variables |
| 590 |
real( kind = dp ) :: sigma |
| 591 |
real( kind = dp ) :: sigma2 |
| 592 |
real( kind = dp ) :: sigma6 |
| 593 |
real( kind = dp ) :: epslon |
| 594 |
|
| 595 |
real( kind = dp ) :: rcut |
| 596 |
real( kind = dp ) :: rcut2 |
| 597 |
real( kind = dp ) :: rcut6 |
| 598 |
real( kind = dp ) :: r2 |
| 599 |
real( kind = dp ) :: r6 |
| 600 |
|
| 601 |
real( kind = dp ) :: t6 |
| 602 |
real( kind = dp ) :: t12 |
| 603 |
real( kind = dp ) :: tp6 |
| 604 |
real( kind = dp ) :: tp12 |
| 605 |
real( kind = dp ) :: delta |
| 606 |
|
| 607 |
logical :: doSec = .false. |
| 608 |
|
| 609 |
integer :: errorStat |
| 610 |
|
| 611 |
!! Optional Argument Checking |
| 612 |
! Check to see if we need to do second derivatives |
| 613 |
|
| 614 |
if (present(d2)) doSec = .true. |
| 615 |
if (present(status)) status = 0 |
| 616 |
|
| 617 |
! Look up the correct parameters in the mixing matrix |
| 618 |
sigma = ljMixed(atype1%atype_ident,atype2_atype_ident)%sigma |
| 619 |
sigma2 = ljMixed(atype1%atype_ident,atype2_atype_ident)%sigma2 |
| 620 |
sigma6 = ljMixed(atype1%atype_ident,atype2_atype_ident)%sigma6 |
| 621 |
epslon = ljMixed(atype1%atype_ident,atype2_atype_ident)%epslon |
| 622 |
|
| 623 |
|
| 624 |
|
| 625 |
call getRcut(rcut,rcut2=rcut2,rcut6=rcut6,status=errorStat) |
| 626 |
|
| 627 |
r2 = r * r |
| 628 |
r6 = r2 * r2 * r2 |
| 629 |
|
| 630 |
t6 = sigma6/ r6 |
| 631 |
t12 = t6 * t6 |
| 632 |
|
| 633 |
|
| 634 |
|
| 635 |
tp6 = sigma6 / rcut6 |
| 636 |
tp12 = tp6*tp6 |
| 637 |
|
| 638 |
delta = -4.0E0_DP*epsilon * (tp12 - tp6) |
| 639 |
|
| 640 |
if (r.le.rcut) then |
| 641 |
u = 4.0E0_DP * epsilon * (t12 - t6) + delta |
| 642 |
dudr = 24.0E0_DP * epsilon * (t6 - 2.0E0_DP*t12) / r |
| 643 |
if(doSec) d2 = 24.0E0_DP * epsilon * (26.0E0_DP*t12 - 7.0E0_DP*t6)/r/r |
| 644 |
else |
| 645 |
u = 0.0E0_DP |
| 646 |
dudr = 0.0E0_DP |
| 647 |
if(doSec) d2 = 0.0E0_DP |
| 648 |
endif |
| 649 |
|
| 650 |
return |
| 651 |
|
| 652 |
|
| 653 |
|
| 654 |
end subroutine getLjPot |
| 655 |
|
| 656 |
|
| 657 |
!! Calculates the mixing for sigma or epslon based on character string |
| 658 |
function calcLJMix(thisParam,param1,param2,status) result(myMixParam) |
| 659 |
character(len=*) :: thisParam |
| 660 |
real(kind = dp) :: param1 |
| 661 |
real(kind = dp) :: param2 |
| 662 |
real(kind = dp ) :: myMixParam |
| 663 |
integer, optional :: status |
| 664 |
|
| 665 |
|
| 666 |
myMixParam = 0.0_dp |
| 667 |
|
| 668 |
if (present(status)) status = 0 |
| 669 |
|
| 670 |
select case (thisParam) |
| 671 |
|
| 672 |
case ("sigma") |
| 673 |
myMixParam = 0.5_dp * (param1 + param2) |
| 674 |
case ("epslon") |
| 675 |
myMixParam = sqrt(param1 * param2) |
| 676 |
case default |
| 677 |
status = -1 |
| 678 |
end select |
| 679 |
|
| 680 |
end function calcLJMix |
| 681 |
|
| 682 |
|
| 683 |
|
| 684 |
end module lj_ff |
