ViewVC Help
View File | Revision Log | Show Annotations | View Changeset | Root Listing
root/group/trunk/mdtools/md_code/Thermo.cpp
Revision: 264
Committed: Tue Feb 4 20:16:08 2003 UTC (21 years, 5 months ago) by chuckv
File size: 7261 byte(s)
Log Message:
Fixed bug with pot energy.

File Contents

# Content
1 #include <cmath>
2 #include <iostream>
3 using namespace std;
4
5 #ifdef IS_MPI
6 #include <mpi.h>
7 #include <mpi++.h>
8 #endif //is_mpi
9
10 #include "Thermo.hpp"
11 #include "SRI.hpp"
12 #include "LRI.hpp"
13 #include "Integrator.hpp"
14
15 #define BASE_SEED 123456789
16
17 Thermo::Thermo( SimInfo* the_entry_plug ) {
18 entry_plug = the_entry_plug;
19 int baseSeed = BASE_SEED;
20
21 gaussStream = new gaussianSPRNG( baseSeed );
22 }
23
24 Thermo::~Thermo(){
25 delete gaussStream;
26 }
27
28 double Thermo::getKinetic(){
29
30 const double e_convert = 4.184E-4; // convert kcal/mol -> (amu A^2)/fs^2
31 double vx2, vy2, vz2;
32 double kinetic, v_sqr;
33 int kl;
34 double jx2, jy2, jz2; // the square of the angular momentums
35
36 DirectionalAtom *dAtom;
37
38 int n_atoms;
39 double kinetic_global;
40 Atom** atoms;
41
42
43 n_atoms = entry_plug->n_atoms;
44 atoms = entry_plug->atoms;
45
46 kinetic = 0.0;
47 kinetic_global = 0.0;
48 for( kl=0; kl < n_atoms; kl++ ){
49
50 vx2 = atoms[kl]->get_vx() * atoms[kl]->get_vx();
51 vy2 = atoms[kl]->get_vy() * atoms[kl]->get_vy();
52 vz2 = atoms[kl]->get_vz() * atoms[kl]->get_vz();
53
54 v_sqr = vx2 + vy2 + vz2;
55 kinetic += atoms[kl]->getMass() * v_sqr;
56
57 if( atoms[kl]->isDirectional() ){
58
59 dAtom = (DirectionalAtom *)atoms[kl];
60
61 jx2 = dAtom->getJx() * dAtom->getJx();
62 jy2 = dAtom->getJy() * dAtom->getJy();
63 jz2 = dAtom->getJz() * dAtom->getJz();
64
65 kinetic += (jx2 / dAtom->getIxx()) + (jy2 / dAtom->getIyy())
66 + (jz2 / dAtom->getIzz());
67 }
68 }
69 #ifdef IS_MPI
70 MPI::COMM_WORLD.Allreduce(&kinetic,&kinetic_global,1,MPI_DOUBLE,MPI_SUM);
71 kinetic = kinetic_global;
72 #endif //is_mpi
73
74 kinetic = kinetic * 0.5 / e_convert;
75
76 return kinetic;
77 }
78
79 double Thermo::getPotential(){
80
81 double potential;
82 double potential_global;
83 int el, nSRI;
84 SRI** sris;
85
86 sris = entry_plug->sr_interactions;
87 nSRI = entry_plug->n_SRI;
88
89 potential = 0.0;
90 potential_global = 0.0;
91 potential += entry_plug->lrPot;
92
93 // std::cerr << "long range potential: " << potential << "\n";
94 for( el=0; el<nSRI; el++ ){
95
96 potential += sris[el]->get_potential();
97 }
98
99 // Get total potential for entire system from MPI.
100 #ifdef IS_MPI
101 MPI::COMM_WORLD.Allreduce(&potential,&potential_global,1,MPI_DOUBLE,MPI_SUM);
102 potential = potential_global;
103
104 #endif // is_mpi
105
106 return potential;
107 }
108
109 double Thermo::getTotalE(){
110
111 double total;
112
113 total = this->getKinetic() + this->getPotential();
114 return total;
115 }
116
117 double Thermo::getTemperature(){
118
119 const double kb = 1.9872179E-3; // boltzman's constant in kcal/(mol K)
120 double temperature;
121
122 int ndf = 3 * entry_plug->n_atoms + 3 * entry_plug->n_oriented
123 - entry_plug->n_constraints - 3;
124
125 temperature = ( 2.0 * this->getKinetic() ) / ( ndf * kb );
126 return temperature;
127 }
128
129 double Thermo::getPressure(){
130
131 // const double conv_Pa_atm = 9.901E-6; // convert Pa -> atm
132 // const double conv_internal_Pa = 1.661E-7; //convert amu/(fs^2 A) -> Pa
133 // const double conv_A_m = 1.0E-10; //convert A -> m
134
135 return 0.0;
136 }
137
138 void Thermo::velocitize() {
139
140 double x,y;
141 double vx, vy, vz;
142 double jx, jy, jz;
143 int i, vr, vd; // velocity randomizer loop counters
144 double vdrift[3];
145 double mtot = 0.0;
146 double vbar;
147 const double kb = 8.31451e-7; // kb in amu, angstroms, fs, etc.
148 double av2;
149 double kebar;
150 int ndf; // number of degrees of freedom
151 int ndfRaw; // the raw number of degrees of freedom
152 int n_atoms;
153 Atom** atoms;
154 DirectionalAtom* dAtom;
155 double temperature;
156 int n_oriented;
157 int n_constraints;
158
159 atoms = entry_plug->atoms;
160 n_atoms = entry_plug->n_atoms;
161 temperature = entry_plug->target_temp;
162 n_oriented = entry_plug->n_oriented;
163 n_constraints = entry_plug->n_constraints;
164
165
166 ndfRaw = 3 * n_atoms + 3 * n_oriented;
167 ndf = ndfRaw - n_constraints - 3;
168 kebar = kb * temperature * (double)ndf / ( 2.0 * (double)ndfRaw );
169
170 for(vr = 0; vr < n_atoms; vr++){
171
172 // uses equipartition theory to solve for vbar in angstrom/fs
173
174 av2 = 2.0 * kebar / atoms[vr]->getMass();
175 vbar = sqrt( av2 );
176
177 // vbar = sqrt( 8.31451e-7 * temperature / atoms[vr]->getMass() );
178
179 // picks random velocities from a gaussian distribution
180 // centered on vbar
181 #ifndef USE_SPRNG
182 /* If we are using mpi, we need to use the SPRNG random
183 generator. The non drand48 generator will just repeat
184 the same numbers for every node creating a non-gaussian
185 distribution for the simulation. drand48 is fine for the
186 single processor version of the code, but SPRNG should
187 still be preferred for consistency.
188 */
189
190 #ifdef IS_MPI
191 #error "SPRNG random number generator must be used for MPI"
192 #else
193 // warning "Using drand48 for random number generation"
194 #endif // is_mpi
195
196 x = drand48();
197 y = drand48();
198 vx = vbar * sqrt( -2.0 * log(x)) * cos(2 * M_PI * y);
199
200 x = drand48();
201 y = drand48();
202 vy = vbar * sqrt( -2.0 * log(x)) * cos(2 * M_PI * y);
203
204 x = drand48();
205 y = drand48();
206 vz = vbar * sqrt( -2.0 * log(x)) * cos(2 * M_PI * y);
207
208 #endif // use_spring
209
210 #ifdef USE_SPRNG
211 vx = vbar * gaussStream->getGaussian();
212 vy = vbar * gaussStream->getGaussian();
213 vz = vbar * gaussStream->getGaussian();
214 #endif // use_spring
215
216 atoms[vr]->set_vx( vx );
217 atoms[vr]->set_vy( vy );
218 atoms[vr]->set_vz( vz );
219 }
220
221 // Corrects for the center of mass drift.
222 // sums all the momentum and divides by total mass.
223
224 mtot = 0.0;
225 vdrift[0] = 0.0;
226 vdrift[1] = 0.0;
227 vdrift[2] = 0.0;
228 for(vd = 0; vd < n_atoms; vd++){
229
230 vdrift[0] += atoms[vd]->get_vx() * atoms[vd]->getMass();
231 vdrift[1] += atoms[vd]->get_vy() * atoms[vd]->getMass();
232 vdrift[2] += atoms[vd]->get_vz() * atoms[vd]->getMass();
233
234 mtot = mtot + atoms[vd]->getMass();
235 }
236
237 for (vd = 0; vd < 3; vd++) {
238 vdrift[vd] = vdrift[vd] / mtot;
239 }
240
241 for(vd = 0; vd < n_atoms; vd++){
242
243 vx = atoms[vd]->get_vx();
244 vy = atoms[vd]->get_vy();
245 vz = atoms[vd]->get_vz();
246
247
248 vx -= vdrift[0];
249 vy -= vdrift[1];
250 vz -= vdrift[2];
251
252 atoms[vd]->set_vx(vx);
253 atoms[vd]->set_vy(vy);
254 atoms[vd]->set_vz(vz);
255 }
256 if( n_oriented ){
257
258 for( i=0; i<n_atoms; i++ ){
259
260 if( atoms[i]->isDirectional() ){
261
262 dAtom = (DirectionalAtom *)atoms[i];
263
264 #ifndef USE_SPRNG
265
266 #ifdef IS_MPI
267 #error "SPRNG random number generator must be used for MPI"
268 #else // is_mpi
269 //warning "Using drand48 for random number generation"
270 #endif // is_MPI
271
272 vbar = sqrt( 2.0 * kebar * dAtom->getIxx() );
273 x = drand48();
274 y = drand48();
275 jx = vbar * sqrt( -2.0 * log(x)) * cos(2 * M_PI * y);
276
277 vbar = sqrt( 2.0 * kebar * dAtom->getIyy() );
278 x = drand48();
279 y = drand48();
280 jy = vbar * sqrt( -2.0 * log(x)) * cos(2 * M_PI * y);
281
282 vbar = sqrt( 2.0 * kebar * dAtom->getIzz() );
283 x = drand48();
284 y = drand48();
285 jz = vbar * sqrt( -2.0 * log(x)) * cos(2 * M_PI * y);
286
287 #else //use_sprng
288
289 vbar = sqrt( 2.0 * kebar * dAtom->getIxx() );
290 jx = vbar * gaussStream->getGaussian();
291
292 vbar = sqrt( 2.0 * kebar * dAtom->getIyy() );
293 jy = vbar * gaussStream->getGaussian();
294
295 vbar = sqrt( 2.0 * kebar * dAtom->getIzz() );
296 jz = vbar * gaussStream->getGaussian();
297 #endif //use_sprng
298
299 dAtom->setJx( jx );
300 dAtom->setJy( jy );
301 dAtom->setJz( jz );
302 }
303 }
304 }
305 }