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root/group/trunk/OOPSE/libmdtools/Thermo.cpp
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Comparing trunk/OOPSE/libmdtools/Thermo.cpp (file contents):
Revision 458 by gezelter, Fri Apr 4 19:47:19 2003 UTC vs.
Revision 574 by gezelter, Tue Jul 8 20:56:10 2003 UTC

# Line 134 | Line 134 | double Thermo::getPressure(){
134    return temperature;
135   }
136  
137 < double Thermo::getPressure(){
138 <  // returns pressure in units amu*fs^-2*Ang^-1
137 > double Thermo::getEnthalpy() {
138 >
139 >  const double e_convert = 4.184E-4; // convert kcal/mol -> (amu A^2)/fs^2
140 >  double u, p, v;
141 >  double press[9];
142 >
143 >  u = this->getTotalE();
144 >
145 >  this->getPressureTensor(press);
146 >  p = (press[0] + press[4] + press[8]) / 3.0;
147 >
148 >  v = this->getVolume();
149 >
150 >  return (u + (p*v)/e_convert);
151 > }
152 >
153 > double Thermo::getVolume() {
154 >
155 >  double volume;
156 >  double Hmat[9];
157 >
158 >  entry_plug->getBoxM(Hmat);
159 >
160 >  // volume = h1 (dot) h2 (cross) h3
161 >
162 >  volume = Hmat[0] * ( (Hmat[4]*Hmat[8]) - (Hmat[7]*Hmat[5]) )
163 >         + Hmat[1] * ( (Hmat[5]*Hmat[6]) - (Hmat[8]*Hmat[3]) )
164 >         + Hmat[2] * ( (Hmat[3]*Hmat[7]) - (Hmat[6]*Hmat[4]) );
165 >
166 >  return volume;
167 > }
168 >
169 > double Thermo::getPressure() {
170 >
171 >  // Relies on the calculation of the full molecular pressure tensor
172 >  
173 >  const double p_convert = 1.63882576e8;
174 >  double press[9];
175 >  double pressure;
176 >
177 >  this->getPressureTensor(press);
178 >
179 >  pressure = p_convert * (press[0] + press[4] + press[8]) / 3.0;
180 >
181 >  return pressure;
182 > }
183 >
184 >
185 > void Thermo::getPressureTensor(double press[9]){
186 >  // returns pressure tensor in units amu*fs^-2*Ang^-1
187    // routine derived via viral theorem description in:
188    // Paci, E. and Marchi, M. J.Phys.Chem. 1996, 100, 4314-4322
189  
190 <  return 0.0;
190 >  const double e_convert = 4.184e-4;
191 >
192 >  double molmass, volume;
193 >  double vcom[3];
194 >  double p_local[9], p_global[9];
195 >  double theBox[3];
196 >  //double* tau;
197 >  int i, nMols;
198 >  Molecule* molecules;
199 >
200 >  nMols = entry_plug->n_mol;
201 >  molecules = entry_plug->molecules;
202 >  //tau = entry_plug->tau;
203 >
204 >  // use velocities of molecular centers of mass and molecular masses:
205 >  for (i=0; i < 9; i++) {    
206 >    p_local[i] = 0.0;
207 >    p_global[i] = 0.0;
208 >  }
209 >
210 >  for (i=0; i < nMols; i++) {
211 >    molmass = molecules[i].getCOMvel(vcom);
212 >
213 >    p_local[0] += molmass * (vcom[0] * vcom[0]);
214 >    p_local[1] += molmass * (vcom[0] * vcom[1]);
215 >    p_local[2] += molmass * (vcom[0] * vcom[2]);
216 >    p_local[3] += molmass * (vcom[1] * vcom[0]);
217 >    p_local[4] += molmass * (vcom[1] * vcom[1]);
218 >    p_local[5] += molmass * (vcom[1] * vcom[2]);
219 >    p_local[6] += molmass * (vcom[2] * vcom[0]);
220 >    p_local[7] += molmass * (vcom[2] * vcom[1]);
221 >    p_local[8] += molmass * (vcom[2] * vcom[2]);
222 >  }
223 >
224 >  // Get total for entire system from MPI.
225 >
226 > #ifdef IS_MPI
227 >  MPI_Allreduce(p_local,p_global,9,MPI_DOUBLE, MPI_SUM, MPI_COMM_WORLD);
228 > #else
229 >  for (i=0; i<9; i++) {
230 >    p_global[i] = p_local[i];
231 >  }
232 > #endif // is_mpi
233 >
234 >  volume = entry_plug->boxVol;
235 >
236 >  for(i=0; i<9; i++) {
237 >    press[i] = (p_global[i] - entry_plug->tau[i]*e_convert) / volume;
238 >  }
239   }
240  
241   void Thermo::velocitize() {

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