1 |
/* |
2 |
* Copyright (c) 2005 The University of Notre Dame. All Rights Reserved. |
3 |
* |
4 |
* The University of Notre Dame grants you ("Licensee") a |
5 |
* non-exclusive, royalty free, license to use, modify and |
6 |
* redistribute this software in source and binary code form, provided |
7 |
* that the following conditions are met: |
8 |
* |
9 |
* 1. Redistributions of source code must retain the above copyright |
10 |
* notice, this list of conditions and the following disclaimer. |
11 |
* |
12 |
* 2. Redistributions in binary form must reproduce the above copyright |
13 |
* notice, this list of conditions and the following disclaimer in the |
14 |
* documentation and/or other materials provided with the |
15 |
* distribution. |
16 |
* |
17 |
* This software is provided "AS IS," without a warranty of any |
18 |
* kind. All express or implied conditions, representations and |
19 |
* warranties, including any implied warranty of merchantability, |
20 |
* fitness for a particular purpose or non-infringement, are hereby |
21 |
* excluded. The University of Notre Dame and its licensors shall not |
22 |
* be liable for any damages suffered by licensee as a result of |
23 |
* using, modifying or distributing the software or its |
24 |
* derivatives. In no event will the University of Notre Dame or its |
25 |
* licensors be liable for any lost revenue, profit or data, or for |
26 |
* direct, indirect, special, consequential, incidental or punitive |
27 |
* damages, however caused and regardless of the theory of liability, |
28 |
* arising out of the use of or inability to use software, even if the |
29 |
* University of Notre Dame has been advised of the possibility of |
30 |
* such damages. |
31 |
* |
32 |
* SUPPORT OPEN SCIENCE! If you use OpenMD or its source code in your |
33 |
* research, please cite the appropriate papers when you publish your |
34 |
* work. Good starting points are: |
35 |
* |
36 |
* [1] Meineke, et al., J. Comp. Chem. 26, 252-271 (2005). |
37 |
* [2] Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006). |
38 |
* [3] Sun, Lin & Gezelter, J. Chem. Phys. 128, 24107 (2008). |
39 |
* [4] Kuang & Gezelter, J. Chem. Phys. 133, 164101 (2010). |
40 |
* [5] Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011). |
41 |
*/ |
42 |
#include <algorithm> |
43 |
#include <math.h> |
44 |
#include "primitives/RigidBody.hpp" |
45 |
#include "utils/simError.h" |
46 |
#include "utils/NumericConstant.hpp" |
47 |
namespace OpenMD { |
48 |
|
49 |
RigidBody::RigidBody() : StuntDouble(otRigidBody, &Snapshot::rigidbodyData), |
50 |
inertiaTensor_(0.0){ |
51 |
} |
52 |
|
53 |
void RigidBody::setPrevA(const RotMat3x3d& a) { |
54 |
((snapshotMan_->getPrevSnapshot())->*storage_).aMat[localIndex_] = a; |
55 |
|
56 |
for (unsigned int i = 0 ; i < atoms_.size(); ++i){ |
57 |
if (atoms_[i]->isDirectional()) { |
58 |
atoms_[i]->setPrevA(refOrients_[i].transpose() * a); |
59 |
} |
60 |
} |
61 |
|
62 |
} |
63 |
|
64 |
|
65 |
void RigidBody::setA(const RotMat3x3d& a) { |
66 |
((snapshotMan_->getCurrentSnapshot())->*storage_).aMat[localIndex_] = a; |
67 |
|
68 |
for (unsigned int i = 0 ; i < atoms_.size(); ++i){ |
69 |
if (atoms_[i]->isDirectional()) { |
70 |
atoms_[i]->setA(refOrients_[i].transpose() * a); |
71 |
} |
72 |
} |
73 |
} |
74 |
|
75 |
void RigidBody::setA(const RotMat3x3d& a, int snapshotNo) { |
76 |
((snapshotMan_->getSnapshot(snapshotNo))->*storage_).aMat[localIndex_] = a; |
77 |
|
78 |
//((snapshotMan_->getSnapshot(snapshotNo))->*storage_).electroFrame[localIndex_] = a.transpose() * sU_; |
79 |
|
80 |
for (unsigned int i = 0 ; i < atoms_.size(); ++i){ |
81 |
if (atoms_[i]->isDirectional()) { |
82 |
atoms_[i]->setA(refOrients_[i].transpose() * a, snapshotNo); |
83 |
} |
84 |
} |
85 |
|
86 |
} |
87 |
|
88 |
Mat3x3d RigidBody::getI() { |
89 |
return inertiaTensor_; |
90 |
} |
91 |
|
92 |
std::vector<RealType> RigidBody::getGrad() { |
93 |
std::vector<RealType> grad(6, 0.0); |
94 |
Vector3d force; |
95 |
Vector3d torque; |
96 |
Vector3d myEuler; |
97 |
RealType phi, theta; |
98 |
// RealType psi; |
99 |
RealType cphi, sphi, ctheta, stheta; |
100 |
Vector3d ephi; |
101 |
Vector3d etheta; |
102 |
Vector3d epsi; |
103 |
|
104 |
force = getFrc(); |
105 |
torque =getTrq(); |
106 |
myEuler = getA().toEulerAngles(); |
107 |
|
108 |
phi = myEuler[0]; |
109 |
theta = myEuler[1]; |
110 |
// psi = myEuler[2]; |
111 |
|
112 |
cphi = cos(phi); |
113 |
sphi = sin(phi); |
114 |
ctheta = cos(theta); |
115 |
stheta = sin(theta); |
116 |
|
117 |
// get unit vectors along the phi, theta and psi rotation axes |
118 |
|
119 |
ephi[0] = 0.0; |
120 |
ephi[1] = 0.0; |
121 |
ephi[2] = 1.0; |
122 |
|
123 |
//etheta[0] = -sphi; |
124 |
//etheta[1] = cphi; |
125 |
//etheta[2] = 0.0; |
126 |
|
127 |
etheta[0] = cphi; |
128 |
etheta[1] = sphi; |
129 |
etheta[2] = 0.0; |
130 |
|
131 |
epsi[0] = stheta * cphi; |
132 |
epsi[1] = stheta * sphi; |
133 |
epsi[2] = ctheta; |
134 |
|
135 |
//gradient is equal to -force |
136 |
for (int j = 0 ; j<3; j++) |
137 |
grad[j] = -force[j]; |
138 |
|
139 |
for (int j = 0; j < 3; j++ ) { |
140 |
|
141 |
grad[3] += torque[j]*ephi[j]; |
142 |
grad[4] += torque[j]*etheta[j]; |
143 |
grad[5] += torque[j]*epsi[j]; |
144 |
|
145 |
} |
146 |
|
147 |
return grad; |
148 |
} |
149 |
|
150 |
void RigidBody::accept(BaseVisitor* v) { |
151 |
v->visit(this); |
152 |
} |
153 |
|
154 |
/**@todo need modification */ |
155 |
void RigidBody::calcRefCoords() { |
156 |
RealType mtmp; |
157 |
Vector3d refCOM(0.0); |
158 |
mass_ = 0.0; |
159 |
for (std::size_t i = 0; i < atoms_.size(); ++i) { |
160 |
mtmp = atoms_[i]->getMass(); |
161 |
mass_ += mtmp; |
162 |
refCOM += refCoords_[i]*mtmp; |
163 |
} |
164 |
refCOM /= mass_; |
165 |
|
166 |
// Next, move the origin of the reference coordinate system to the COM: |
167 |
for (std::size_t i = 0; i < atoms_.size(); ++i) { |
168 |
refCoords_[i] -= refCOM; |
169 |
} |
170 |
|
171 |
// Moment of Inertia calculation |
172 |
Mat3x3d Itmp(0.0); |
173 |
for (std::size_t i = 0; i < atoms_.size(); i++) { |
174 |
Mat3x3d IAtom(0.0); |
175 |
mtmp = atoms_[i]->getMass(); |
176 |
IAtom -= outProduct(refCoords_[i], refCoords_[i]) * mtmp; |
177 |
RealType r2 = refCoords_[i].lengthSquare(); |
178 |
IAtom(0, 0) += mtmp * r2; |
179 |
IAtom(1, 1) += mtmp * r2; |
180 |
IAtom(2, 2) += mtmp * r2; |
181 |
Itmp += IAtom; |
182 |
|
183 |
//project the inertial moment of directional atoms into this rigid body |
184 |
if (atoms_[i]->isDirectional()) { |
185 |
Itmp += refOrients_[i].transpose() * atoms_[i]->getI() * refOrients_[i]; |
186 |
} |
187 |
} |
188 |
|
189 |
// std::cout << Itmp << std::endl; |
190 |
|
191 |
//diagonalize |
192 |
Vector3d evals; |
193 |
Mat3x3d::diagonalize(Itmp, evals, sU_); |
194 |
|
195 |
// zero out I and then fill the diagonals with the moments of inertia: |
196 |
inertiaTensor_(0, 0) = evals[0]; |
197 |
inertiaTensor_(1, 1) = evals[1]; |
198 |
inertiaTensor_(2, 2) = evals[2]; |
199 |
|
200 |
int nLinearAxis = 0; |
201 |
for (int i = 0; i < 3; i++) { |
202 |
if (fabs(evals[i]) < OpenMD::epsilon) { |
203 |
linear_ = true; |
204 |
linearAxis_ = i; |
205 |
++ nLinearAxis; |
206 |
} |
207 |
} |
208 |
|
209 |
if (nLinearAxis > 1) { |
210 |
sprintf( painCave.errMsg, |
211 |
"RigidBody error.\n" |
212 |
"\tOpenMD found more than one axis in this rigid body with a vanishing \n" |
213 |
"\tmoment of inertia. This can happen in one of three ways:\n" |
214 |
"\t 1) Only one atom was specified, or \n" |
215 |
"\t 2) All atoms were specified at the same location, or\n" |
216 |
"\t 3) The programmers did something stupid.\n" |
217 |
"\tIt is silly to use a rigid body to describe this situation. Be smarter.\n" |
218 |
); |
219 |
painCave.isFatal = 1; |
220 |
simError(); |
221 |
} |
222 |
|
223 |
} |
224 |
|
225 |
void RigidBody::calcForcesAndTorques() { |
226 |
Vector3d afrc; |
227 |
Vector3d atrq; |
228 |
Vector3d apos; |
229 |
Vector3d rpos; |
230 |
Vector3d frc(0.0); |
231 |
Vector3d trq(0.0); |
232 |
Vector3d pos = this->getPos(); |
233 |
for (unsigned int i = 0; i < atoms_.size(); i++) { |
234 |
|
235 |
afrc = atoms_[i]->getFrc(); |
236 |
apos = atoms_[i]->getPos(); |
237 |
rpos = apos - pos; |
238 |
|
239 |
frc += afrc; |
240 |
|
241 |
trq[0] += rpos[1]*afrc[2] - rpos[2]*afrc[1]; |
242 |
trq[1] += rpos[2]*afrc[0] - rpos[0]*afrc[2]; |
243 |
trq[2] += rpos[0]*afrc[1] - rpos[1]*afrc[0]; |
244 |
|
245 |
// If the atom has a torque associated with it, then we also need to |
246 |
// migrate the torques onto the center of mass: |
247 |
|
248 |
if (atoms_[i]->isDirectional()) { |
249 |
atrq = atoms_[i]->getTrq(); |
250 |
trq += atrq; |
251 |
} |
252 |
} |
253 |
addFrc(frc); |
254 |
addTrq(trq); |
255 |
} |
256 |
|
257 |
Mat3x3d RigidBody::calcForcesAndTorquesAndVirial() { |
258 |
Vector3d afrc; |
259 |
Vector3d atrq; |
260 |
Vector3d apos; |
261 |
Vector3d rpos; |
262 |
Vector3d dfrc; |
263 |
Vector3d frc(0.0); |
264 |
Vector3d trq(0.0); |
265 |
Vector3d pos = this->getPos(); |
266 |
Mat3x3d tau_(0.0); |
267 |
|
268 |
for (unsigned int i = 0; i < atoms_.size(); i++) { |
269 |
|
270 |
afrc = atoms_[i]->getFrc(); |
271 |
apos = atoms_[i]->getPos(); |
272 |
rpos = apos - pos; |
273 |
|
274 |
frc += afrc; |
275 |
|
276 |
trq[0] += rpos[1]*afrc[2] - rpos[2]*afrc[1]; |
277 |
trq[1] += rpos[2]*afrc[0] - rpos[0]*afrc[2]; |
278 |
trq[2] += rpos[0]*afrc[1] - rpos[1]*afrc[0]; |
279 |
|
280 |
// If the atom has a torque associated with it, then we also need to |
281 |
// migrate the torques onto the center of mass: |
282 |
|
283 |
if (atoms_[i]->isDirectional()) { |
284 |
atrq = atoms_[i]->getTrq(); |
285 |
trq += atrq; |
286 |
} |
287 |
|
288 |
tau_(0,0) -= rpos[0]*afrc[0]; |
289 |
tau_(0,1) -= rpos[0]*afrc[1]; |
290 |
tau_(0,2) -= rpos[0]*afrc[2]; |
291 |
tau_(1,0) -= rpos[1]*afrc[0]; |
292 |
tau_(1,1) -= rpos[1]*afrc[1]; |
293 |
tau_(1,2) -= rpos[1]*afrc[2]; |
294 |
tau_(2,0) -= rpos[2]*afrc[0]; |
295 |
tau_(2,1) -= rpos[2]*afrc[1]; |
296 |
tau_(2,2) -= rpos[2]*afrc[2]; |
297 |
|
298 |
} |
299 |
addFrc(frc); |
300 |
addTrq(trq); |
301 |
return tau_; |
302 |
} |
303 |
|
304 |
void RigidBody::updateAtoms() { |
305 |
unsigned int i; |
306 |
Vector3d ref; |
307 |
Vector3d apos; |
308 |
DirectionalAtom* dAtom; |
309 |
Vector3d pos = getPos(); |
310 |
RotMat3x3d a = getA(); |
311 |
|
312 |
for (i = 0; i < atoms_.size(); i++) { |
313 |
|
314 |
ref = body2Lab(refCoords_[i]); |
315 |
|
316 |
apos = pos + ref; |
317 |
|
318 |
atoms_[i]->setPos(apos); |
319 |
|
320 |
if (atoms_[i]->isDirectional()) { |
321 |
|
322 |
dAtom = (DirectionalAtom *) atoms_[i]; |
323 |
dAtom->setA(refOrients_[i].transpose() * a); |
324 |
} |
325 |
|
326 |
} |
327 |
|
328 |
} |
329 |
|
330 |
|
331 |
void RigidBody::updateAtoms(int frame) { |
332 |
unsigned int i; |
333 |
Vector3d ref; |
334 |
Vector3d apos; |
335 |
DirectionalAtom* dAtom; |
336 |
Vector3d pos = getPos(frame); |
337 |
RotMat3x3d a = getA(frame); |
338 |
|
339 |
for (i = 0; i < atoms_.size(); i++) { |
340 |
|
341 |
ref = body2Lab(refCoords_[i], frame); |
342 |
|
343 |
apos = pos + ref; |
344 |
|
345 |
atoms_[i]->setPos(apos, frame); |
346 |
|
347 |
if (atoms_[i]->isDirectional()) { |
348 |
|
349 |
dAtom = (DirectionalAtom *) atoms_[i]; |
350 |
dAtom->setA(refOrients_[i].transpose() * a, frame); |
351 |
} |
352 |
|
353 |
} |
354 |
|
355 |
} |
356 |
|
357 |
void RigidBody::updateAtomVel() { |
358 |
Mat3x3d skewMat;; |
359 |
|
360 |
Vector3d ji = getJ(); |
361 |
Mat3x3d I = getI(); |
362 |
|
363 |
skewMat(0, 0) =0; |
364 |
skewMat(0, 1) = ji[2] /I(2, 2); |
365 |
skewMat(0, 2) = -ji[1] /I(1, 1); |
366 |
|
367 |
skewMat(1, 0) = -ji[2] /I(2, 2); |
368 |
skewMat(1, 1) = 0; |
369 |
skewMat(1, 2) = ji[0]/I(0, 0); |
370 |
|
371 |
skewMat(2, 0) =ji[1] /I(1, 1); |
372 |
skewMat(2, 1) = -ji[0]/I(0, 0); |
373 |
skewMat(2, 2) = 0; |
374 |
|
375 |
Mat3x3d mat = (getA() * skewMat).transpose(); |
376 |
Vector3d rbVel = getVel(); |
377 |
|
378 |
|
379 |
Vector3d velRot; |
380 |
for (unsigned int i = 0 ; i < refCoords_.size(); ++i) { |
381 |
atoms_[i]->setVel(rbVel + mat * refCoords_[i]); |
382 |
} |
383 |
|
384 |
} |
385 |
|
386 |
void RigidBody::updateAtomVel(int frame) { |
387 |
Mat3x3d skewMat;; |
388 |
|
389 |
Vector3d ji = getJ(frame); |
390 |
Mat3x3d I = getI(); |
391 |
|
392 |
skewMat(0, 0) =0; |
393 |
skewMat(0, 1) = ji[2] /I(2, 2); |
394 |
skewMat(0, 2) = -ji[1] /I(1, 1); |
395 |
|
396 |
skewMat(1, 0) = -ji[2] /I(2, 2); |
397 |
skewMat(1, 1) = 0; |
398 |
skewMat(1, 2) = ji[0]/I(0, 0); |
399 |
|
400 |
skewMat(2, 0) =ji[1] /I(1, 1); |
401 |
skewMat(2, 1) = -ji[0]/I(0, 0); |
402 |
skewMat(2, 2) = 0; |
403 |
|
404 |
Mat3x3d mat = (getA(frame) * skewMat).transpose(); |
405 |
Vector3d rbVel = getVel(frame); |
406 |
|
407 |
|
408 |
Vector3d velRot; |
409 |
for (unsigned int i = 0 ; i < refCoords_.size(); ++i) { |
410 |
atoms_[i]->setVel(rbVel + mat * refCoords_[i], frame); |
411 |
} |
412 |
|
413 |
} |
414 |
|
415 |
|
416 |
|
417 |
bool RigidBody::getAtomPos(Vector3d& pos, unsigned int index) { |
418 |
if (index < atoms_.size()) { |
419 |
|
420 |
Vector3d ref = body2Lab(refCoords_[index]); |
421 |
pos = getPos() + ref; |
422 |
return true; |
423 |
} else { |
424 |
std::cerr << index << " is an invalid index, current rigid body contains " |
425 |
<< atoms_.size() << "atoms" << std::endl; |
426 |
return false; |
427 |
} |
428 |
} |
429 |
|
430 |
bool RigidBody::getAtomPos(Vector3d& pos, Atom* atom) { |
431 |
std::vector<Atom*>::iterator i; |
432 |
i = std::find(atoms_.begin(), atoms_.end(), atom); |
433 |
if (i != atoms_.end()) { |
434 |
//RigidBody class makes sure refCoords_ and atoms_ match each other |
435 |
Vector3d ref = body2Lab(refCoords_[i - atoms_.begin()]); |
436 |
pos = getPos() + ref; |
437 |
return true; |
438 |
} else { |
439 |
std::cerr << "Atom " << atom->getGlobalIndex() |
440 |
<<" does not belong to Rigid body "<< getGlobalIndex() << std::endl; |
441 |
return false; |
442 |
} |
443 |
} |
444 |
bool RigidBody::getAtomVel(Vector3d& vel, unsigned int index) { |
445 |
|
446 |
//velRot = $(A\cdot skew(I^{-1}j))^{T}refCoor$ |
447 |
|
448 |
if (index < atoms_.size()) { |
449 |
|
450 |
Vector3d velRot; |
451 |
Mat3x3d skewMat;; |
452 |
Vector3d ref = refCoords_[index]; |
453 |
Vector3d ji = getJ(); |
454 |
Mat3x3d I = getI(); |
455 |
|
456 |
skewMat(0, 0) =0; |
457 |
skewMat(0, 1) = ji[2] /I(2, 2); |
458 |
skewMat(0, 2) = -ji[1] /I(1, 1); |
459 |
|
460 |
skewMat(1, 0) = -ji[2] /I(2, 2); |
461 |
skewMat(1, 1) = 0; |
462 |
skewMat(1, 2) = ji[0]/I(0, 0); |
463 |
|
464 |
skewMat(2, 0) =ji[1] /I(1, 1); |
465 |
skewMat(2, 1) = -ji[0]/I(0, 0); |
466 |
skewMat(2, 2) = 0; |
467 |
|
468 |
velRot = (getA() * skewMat).transpose() * ref; |
469 |
|
470 |
vel =getVel() + velRot; |
471 |
return true; |
472 |
|
473 |
} else { |
474 |
std::cerr << index << " is an invalid index, current rigid body contains " |
475 |
<< atoms_.size() << "atoms" << std::endl; |
476 |
return false; |
477 |
} |
478 |
} |
479 |
|
480 |
bool RigidBody::getAtomVel(Vector3d& vel, Atom* atom) { |
481 |
|
482 |
std::vector<Atom*>::iterator i; |
483 |
i = std::find(atoms_.begin(), atoms_.end(), atom); |
484 |
if (i != atoms_.end()) { |
485 |
return getAtomVel(vel, i - atoms_.begin()); |
486 |
} else { |
487 |
std::cerr << "Atom " << atom->getGlobalIndex() |
488 |
<<" does not belong to Rigid body "<< getGlobalIndex() << std::endl; |
489 |
return false; |
490 |
} |
491 |
} |
492 |
|
493 |
bool RigidBody::getAtomRefCoor(Vector3d& coor, unsigned int index) { |
494 |
if (index < atoms_.size()) { |
495 |
|
496 |
coor = refCoords_[index]; |
497 |
return true; |
498 |
} else { |
499 |
std::cerr << index << " is an invalid index, current rigid body contains " |
500 |
<< atoms_.size() << "atoms" << std::endl; |
501 |
return false; |
502 |
} |
503 |
|
504 |
} |
505 |
|
506 |
bool RigidBody::getAtomRefCoor(Vector3d& coor, Atom* atom) { |
507 |
std::vector<Atom*>::iterator i; |
508 |
i = std::find(atoms_.begin(), atoms_.end(), atom); |
509 |
if (i != atoms_.end()) { |
510 |
//RigidBody class makes sure refCoords_ and atoms_ match each other |
511 |
coor = refCoords_[i - atoms_.begin()]; |
512 |
return true; |
513 |
} else { |
514 |
std::cerr << "Atom " << atom->getGlobalIndex() |
515 |
<<" does not belong to Rigid body "<< getGlobalIndex() << std::endl; |
516 |
return false; |
517 |
} |
518 |
|
519 |
} |
520 |
|
521 |
|
522 |
void RigidBody::addAtom(Atom* at, AtomStamp* ats) { |
523 |
|
524 |
Vector3d coords; |
525 |
Vector3d euler; |
526 |
|
527 |
|
528 |
atoms_.push_back(at); |
529 |
|
530 |
if( !ats->havePosition() ){ |
531 |
sprintf( painCave.errMsg, |
532 |
"RigidBody error.\n" |
533 |
"\tAtom %s does not have a position specified.\n" |
534 |
"\tThis means RigidBody cannot set up reference coordinates.\n", |
535 |
ats->getType().c_str() ); |
536 |
painCave.isFatal = 1; |
537 |
simError(); |
538 |
} |
539 |
|
540 |
coords[0] = ats->getPosX(); |
541 |
coords[1] = ats->getPosY(); |
542 |
coords[2] = ats->getPosZ(); |
543 |
|
544 |
refCoords_.push_back(coords); |
545 |
|
546 |
RotMat3x3d identMat = RotMat3x3d::identity(); |
547 |
|
548 |
if (at->isDirectional()) { |
549 |
|
550 |
if( !ats->haveOrientation() ){ |
551 |
sprintf( painCave.errMsg, |
552 |
"RigidBody error.\n" |
553 |
"\tAtom %s does not have an orientation specified.\n" |
554 |
"\tThis means RigidBody cannot set up reference orientations.\n", |
555 |
ats->getType().c_str() ); |
556 |
painCave.isFatal = 1; |
557 |
simError(); |
558 |
} |
559 |
|
560 |
euler[0] = ats->getEulerPhi() * NumericConstant::PI /180.0; |
561 |
euler[1] = ats->getEulerTheta() * NumericConstant::PI /180.0; |
562 |
euler[2] = ats->getEulerPsi() * NumericConstant::PI /180.0; |
563 |
|
564 |
RotMat3x3d Atmp(euler); |
565 |
refOrients_.push_back(Atmp); |
566 |
|
567 |
}else { |
568 |
refOrients_.push_back(identMat); |
569 |
} |
570 |
|
571 |
|
572 |
} |
573 |
|
574 |
} |
575 |
|