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 ( kind = 2) :: 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 |