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root/group/trunk/OOPSE/libmdtools/Thermo.cpp
Revision: 475
Committed: Tue Apr 8 12:44:18 2003 UTC (21 years, 3 months ago) by gezelter
File size: 7194 byte(s)
Log Message:
Changes to integrate the NVT and NPT ensembles

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 convert = 4.184e-4;
143 double molmass;
144 double vcom[3];
145 double p_local, p_sum, p_mol, virial;
146 double theBox[3];
147 double* tau;
148 int i, nMols;
149 Molecule* molecules;
150
151 nMols = entry_plug->n_mol;
152 molecules = entry_plug->molecules;
153 tau = entry_plug->tau;
154
155 // use velocities of molecular centers of mass and molecular masses:
156 p_local = 0.0;
157
158 for (i=0; i < nMols; i++) {
159 molmass = molecules[i].getCOMvel(vcom);
160 p_local += (vcom[0]*vcom[0] + vcom[1]*vcom[1] + vcom[2]*vcom[2]) * molmass;
161 }
162
163 // Get total for entire system from MPI.
164 #ifdef IS_MPI
165 MPI_Allreduce(&p_local,&p_sum,1,MPI_DOUBLE, MPI_SUM, MPI_COMM_WORLD);
166 #else
167 p_sum = p_local;
168 #endif // is_mpi
169
170 virial = tau[0] + tau[4] + tau[8];
171 entry_plug->getBox(theBox);
172
173 p_mol = (p_sum - virial*convert) / (3.0 * theBox[0] * theBox[1]* theBox[2]);
174
175 return p_mol;
176 }
177
178 void Thermo::velocitize() {
179
180 double x,y;
181 double vx, vy, vz;
182 double jx, jy, jz;
183 int i, vr, vd; // velocity randomizer loop counters
184 double vdrift[3];
185 double vbar;
186 const double kb = 8.31451e-7; // kb in amu, angstroms, fs, etc.
187 double av2;
188 double kebar;
189 int n_atoms;
190 Atom** atoms;
191 DirectionalAtom* dAtom;
192 double temperature;
193 int n_oriented;
194 int n_constraints;
195
196 atoms = entry_plug->atoms;
197 n_atoms = entry_plug->n_atoms;
198 temperature = entry_plug->target_temp;
199 n_oriented = entry_plug->n_oriented;
200 n_constraints = entry_plug->n_constraints;
201
202 kebar = kb * temperature * (double)entry_plug->ndf /
203 ( 2.0 * (double)entry_plug->ndfRaw );
204
205 for(vr = 0; vr < n_atoms; vr++){
206
207 // uses equipartition theory to solve for vbar in angstrom/fs
208
209 av2 = 2.0 * kebar / atoms[vr]->getMass();
210 vbar = sqrt( av2 );
211
212 // vbar = sqrt( 8.31451e-7 * temperature / atoms[vr]->getMass() );
213
214 // picks random velocities from a gaussian distribution
215 // centered on vbar
216
217 vx = vbar * gaussStream->getGaussian();
218 vy = vbar * gaussStream->getGaussian();
219 vz = vbar * gaussStream->getGaussian();
220
221 atoms[vr]->set_vx( vx );
222 atoms[vr]->set_vy( vy );
223 atoms[vr]->set_vz( vz );
224 }
225
226 // Get the Center of Mass drift velocity.
227
228 getCOMVel(vdrift);
229
230 // Corrects for the center of mass drift.
231 // sums all the momentum and divides by total mass.
232
233 for(vd = 0; vd < n_atoms; vd++){
234
235 vx = atoms[vd]->get_vx();
236 vy = atoms[vd]->get_vy();
237 vz = atoms[vd]->get_vz();
238
239 vx -= vdrift[0];
240 vy -= vdrift[1];
241 vz -= vdrift[2];
242
243 atoms[vd]->set_vx(vx);
244 atoms[vd]->set_vy(vy);
245 atoms[vd]->set_vz(vz);
246 }
247 if( n_oriented ){
248
249 for( i=0; i<n_atoms; i++ ){
250
251 if( atoms[i]->isDirectional() ){
252
253 dAtom = (DirectionalAtom *)atoms[i];
254
255 vbar = sqrt( 2.0 * kebar * dAtom->getIxx() );
256 jx = vbar * gaussStream->getGaussian();
257
258 vbar = sqrt( 2.0 * kebar * dAtom->getIyy() );
259 jy = vbar * gaussStream->getGaussian();
260
261 vbar = sqrt( 2.0 * kebar * dAtom->getIzz() );
262 jz = vbar * gaussStream->getGaussian();
263
264 dAtom->setJx( jx );
265 dAtom->setJy( jy );
266 dAtom->setJz( jz );
267 }
268 }
269 }
270 }
271
272 void Thermo::getCOMVel(double vdrift[3]){
273
274 double mtot, mtot_local;
275 double vdrift_local[3];
276 int vd, n_atoms;
277 Atom** atoms;
278
279 // We are very careless here with the distinction between n_atoms and n_local
280 // We should really fix this before someone pokes an eye out.
281
282 n_atoms = entry_plug->n_atoms;
283 atoms = entry_plug->atoms;
284
285 mtot_local = 0.0;
286 vdrift_local[0] = 0.0;
287 vdrift_local[1] = 0.0;
288 vdrift_local[2] = 0.0;
289
290 for(vd = 0; vd < n_atoms; vd++){
291
292 vdrift_local[0] += atoms[vd]->get_vx() * atoms[vd]->getMass();
293 vdrift_local[1] += atoms[vd]->get_vy() * atoms[vd]->getMass();
294 vdrift_local[2] += atoms[vd]->get_vz() * atoms[vd]->getMass();
295
296 mtot_local += atoms[vd]->getMass();
297 }
298
299 #ifdef IS_MPI
300 MPI_Allreduce(&mtot_local,&mtot,1,MPI_DOUBLE,MPI_SUM, MPI_COMM_WORLD);
301 MPI_Allreduce(vdrift_local,vdrift,3,MPI_DOUBLE,MPI_SUM, MPI_COMM_WORLD);
302 #else
303 mtot = mtot_local;
304 for(vd = 0; vd < 3; vd++) {
305 vdrift[vd] = vdrift_local[vd];
306 }
307 #endif
308
309 for (vd = 0; vd < 3; vd++) {
310 vdrift[vd] = vdrift[vd] / mtot;
311 }
312
313 }
314