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root/group/trunk/OOPSE/libmdtools/Thermo.cpp
Revision: 477
Committed: Tue Apr 8 14:34:30 2003 UTC (21 years, 3 months ago) by gezelter
File size: 7255 byte(s)
Log Message:
dt/2 fix in nvt

File Contents

# Content
1 #include <cmath>
2 #include <iostream>
3 using namespace std;
4
5 #ifdef IS_MPI
6 #include <mpi.h>
7 #endif //is_mpi
8
9 #include "Thermo.hpp"
10 #include "SRI.hpp"
11 #include "Integrator.hpp"
12 #include "simError.h"
13
14 #ifdef IS_MPI
15 #define __C
16 #include "mpiSimulation.hpp"
17 #endif // is_mpi
18
19
20 #define BASE_SEED 123456789
21
22 Thermo::Thermo( SimInfo* the_entry_plug ) {
23 entry_plug = the_entry_plug;
24 int baseSeed = BASE_SEED;
25
26 gaussStream = new gaussianSPRNG( baseSeed );
27 }
28
29 Thermo::~Thermo(){
30 delete gaussStream;
31 }
32
33 double Thermo::getKinetic(){
34
35 const double e_convert = 4.184E-4; // convert kcal/mol -> (amu A^2)/fs^2
36 double vx2, vy2, vz2;
37 double kinetic, v_sqr;
38 int kl;
39 double jx2, jy2, jz2; // the square of the angular momentums
40
41 DirectionalAtom *dAtom;
42
43 int n_atoms;
44 double kinetic_global;
45 Atom** atoms;
46
47
48 n_atoms = entry_plug->n_atoms;
49 atoms = entry_plug->atoms;
50
51 kinetic = 0.0;
52 kinetic_global = 0.0;
53 for( kl=0; kl < n_atoms; kl++ ){
54
55 vx2 = atoms[kl]->get_vx() * atoms[kl]->get_vx();
56 vy2 = atoms[kl]->get_vy() * atoms[kl]->get_vy();
57 vz2 = atoms[kl]->get_vz() * atoms[kl]->get_vz();
58
59 v_sqr = vx2 + vy2 + vz2;
60 kinetic += atoms[kl]->getMass() * v_sqr;
61
62 if( atoms[kl]->isDirectional() ){
63
64 dAtom = (DirectionalAtom *)atoms[kl];
65
66 jx2 = dAtom->getJx() * dAtom->getJx();
67 jy2 = dAtom->getJy() * dAtom->getJy();
68 jz2 = dAtom->getJz() * dAtom->getJz();
69
70 kinetic += (jx2 / dAtom->getIxx()) + (jy2 / dAtom->getIyy())
71 + (jz2 / dAtom->getIzz());
72 }
73 }
74 #ifdef IS_MPI
75 MPI_Allreduce(&kinetic,&kinetic_global,1,MPI_DOUBLE,
76 MPI_SUM, MPI_COMM_WORLD);
77 kinetic = kinetic_global;
78 #endif //is_mpi
79
80 kinetic = kinetic * 0.5 / e_convert;
81
82 return kinetic;
83 }
84
85 double Thermo::getPotential(){
86
87 double potential_local;
88 double potential;
89 int el, nSRI;
90 Molecule* molecules;
91
92 molecules = entry_plug->molecules;
93 nSRI = entry_plug->n_SRI;
94
95 potential_local = 0.0;
96 potential = 0.0;
97 potential_local += entry_plug->lrPot;
98
99 for( el=0; el<entry_plug->n_mol; el++ ){
100 potential_local += molecules[el].getPotential();
101 }
102
103 // Get total potential for entire system from MPI.
104 #ifdef IS_MPI
105 MPI_Allreduce(&potential_local,&potential,1,MPI_DOUBLE,
106 MPI_SUM, MPI_COMM_WORLD);
107 #else
108 potential = potential_local;
109 #endif // is_mpi
110
111 #ifdef IS_MPI
112 /*
113 std::cerr << "node " << worldRank << ": after pot = " << potential << "\n";
114 */
115 #endif
116
117 return potential;
118 }
119
120 double Thermo::getTotalE(){
121
122 double total;
123
124 total = this->getKinetic() + this->getPotential();
125 return total;
126 }
127
128 double Thermo::getTemperature(){
129
130 const double kb = 1.9872179E-3; // boltzman's constant in kcal/(mol K)
131 double temperature;
132
133 temperature = ( 2.0 * this->getKinetic() ) / ((double)entry_plug->ndf * kb );
134 return temperature;
135 }
136
137 double Thermo::getPressure(){
138 // returns pressure in units amu*fs^-2*Ang^-1
139 // routine derived via viral theorem description in:
140 // Paci, E. and Marchi, M. J.Phys.Chem. 1996, 100, 4314-4322
141
142 const double e_convert = 4.184e-4;
143 const double p_convert = 1.63882576e8;
144 double molmass;
145 double vcom[3];
146 double p_local, p_sum, p_mol, virial;
147 double theBox[3];
148 double* tau;
149 int i, nMols;
150 Molecule* molecules;
151
152 nMols = entry_plug->n_mol;
153 molecules = entry_plug->molecules;
154 tau = entry_plug->tau;
155
156 // use velocities of molecular centers of mass and molecular masses:
157 p_local = 0.0;
158
159 for (i=0; i < nMols; i++) {
160 molmass = molecules[i].getCOMvel(vcom);
161 p_local += (vcom[0]*vcom[0] + vcom[1]*vcom[1] + vcom[2]*vcom[2]) * molmass;
162 }
163
164 // Get total for entire system from MPI.
165 #ifdef IS_MPI
166 MPI_Allreduce(&p_local,&p_sum,1,MPI_DOUBLE, MPI_SUM, MPI_COMM_WORLD);
167 #else
168 p_sum = p_local;
169 #endif // is_mpi
170
171 virial = tau[0] + tau[4] + tau[8];
172 entry_plug->getBox(theBox);
173
174 p_mol = p_convert * (p_sum - virial*e_convert) /
175 (3.0 * theBox[0] * theBox[1]* theBox[2]);
176
177 return p_mol;
178 }
179
180 void Thermo::velocitize() {
181
182 double x,y;
183 double vx, vy, vz;
184 double jx, jy, jz;
185 int i, vr, vd; // velocity randomizer loop counters
186 double vdrift[3];
187 double vbar;
188 const double kb = 8.31451e-7; // kb in amu, angstroms, fs, etc.
189 double av2;
190 double kebar;
191 int n_atoms;
192 Atom** atoms;
193 DirectionalAtom* dAtom;
194 double temperature;
195 int n_oriented;
196 int n_constraints;
197
198 atoms = entry_plug->atoms;
199 n_atoms = entry_plug->n_atoms;
200 temperature = entry_plug->target_temp;
201 n_oriented = entry_plug->n_oriented;
202 n_constraints = entry_plug->n_constraints;
203
204 kebar = kb * temperature * (double)entry_plug->ndf /
205 ( 2.0 * (double)entry_plug->ndfRaw );
206
207 for(vr = 0; vr < n_atoms; vr++){
208
209 // uses equipartition theory to solve for vbar in angstrom/fs
210
211 av2 = 2.0 * kebar / atoms[vr]->getMass();
212 vbar = sqrt( av2 );
213
214 // vbar = sqrt( 8.31451e-7 * temperature / atoms[vr]->getMass() );
215
216 // picks random velocities from a gaussian distribution
217 // centered on vbar
218
219 vx = vbar * gaussStream->getGaussian();
220 vy = vbar * gaussStream->getGaussian();
221 vz = vbar * gaussStream->getGaussian();
222
223 atoms[vr]->set_vx( vx );
224 atoms[vr]->set_vy( vy );
225 atoms[vr]->set_vz( vz );
226 }
227
228 // Get the Center of Mass drift velocity.
229
230 getCOMVel(vdrift);
231
232 // Corrects for the center of mass drift.
233 // sums all the momentum and divides by total mass.
234
235 for(vd = 0; vd < n_atoms; vd++){
236
237 vx = atoms[vd]->get_vx();
238 vy = atoms[vd]->get_vy();
239 vz = atoms[vd]->get_vz();
240
241 vx -= vdrift[0];
242 vy -= vdrift[1];
243 vz -= vdrift[2];
244
245 atoms[vd]->set_vx(vx);
246 atoms[vd]->set_vy(vy);
247 atoms[vd]->set_vz(vz);
248 }
249 if( n_oriented ){
250
251 for( i=0; i<n_atoms; i++ ){
252
253 if( atoms[i]->isDirectional() ){
254
255 dAtom = (DirectionalAtom *)atoms[i];
256
257 vbar = sqrt( 2.0 * kebar * dAtom->getIxx() );
258 jx = vbar * gaussStream->getGaussian();
259
260 vbar = sqrt( 2.0 * kebar * dAtom->getIyy() );
261 jy = vbar * gaussStream->getGaussian();
262
263 vbar = sqrt( 2.0 * kebar * dAtom->getIzz() );
264 jz = vbar * gaussStream->getGaussian();
265
266 dAtom->setJx( jx );
267 dAtom->setJy( jy );
268 dAtom->setJz( jz );
269 }
270 }
271 }
272 }
273
274 void Thermo::getCOMVel(double vdrift[3]){
275
276 double mtot, mtot_local;
277 double vdrift_local[3];
278 int vd, n_atoms;
279 Atom** atoms;
280
281 // We are very careless here with the distinction between n_atoms and n_local
282 // We should really fix this before someone pokes an eye out.
283
284 n_atoms = entry_plug->n_atoms;
285 atoms = entry_plug->atoms;
286
287 mtot_local = 0.0;
288 vdrift_local[0] = 0.0;
289 vdrift_local[1] = 0.0;
290 vdrift_local[2] = 0.0;
291
292 for(vd = 0; vd < n_atoms; vd++){
293
294 vdrift_local[0] += atoms[vd]->get_vx() * atoms[vd]->getMass();
295 vdrift_local[1] += atoms[vd]->get_vy() * atoms[vd]->getMass();
296 vdrift_local[2] += atoms[vd]->get_vz() * atoms[vd]->getMass();
297
298 mtot_local += atoms[vd]->getMass();
299 }
300
301 #ifdef IS_MPI
302 MPI_Allreduce(&mtot_local,&mtot,1,MPI_DOUBLE,MPI_SUM, MPI_COMM_WORLD);
303 MPI_Allreduce(vdrift_local,vdrift,3,MPI_DOUBLE,MPI_SUM, MPI_COMM_WORLD);
304 #else
305 mtot = mtot_local;
306 for(vd = 0; vd < 3; vd++) {
307 vdrift[vd] = vdrift_local[vd];
308 }
309 #endif
310
311 for (vd = 0; vd < 3; vd++) {
312 vdrift[vd] = vdrift[vd] / mtot;
313 }
314
315 }
316