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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 582 by mmeineke, Wed Jul 9 15:33:46 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 >  return entry_plug->boxVol;
156 > }
157 >
158 > double Thermo::getPressure() {
159 >
160 >  // Relies on the calculation of the full molecular pressure tensor
161 >  
162 >  const double p_convert = 1.63882576e8;
163 >  double press[9];
164 >  double pressure;
165 >
166 >  this->getPressureTensor(press);
167 >
168 >  pressure = p_convert * (press[0] + press[4] + press[8]) / 3.0;
169 >
170 >  return pressure;
171 > }
172 >
173 >
174 > void Thermo::getPressureTensor(double press[9]){
175 >  // returns pressure tensor in units amu*fs^-2*Ang^-1
176    // routine derived via viral theorem description in:
177    // Paci, E. and Marchi, M. J.Phys.Chem. 1996, 100, 4314-4322
178  
179 <  return 0.0;
179 >  const double e_convert = 4.184e-4;
180 >
181 >  double molmass, volume;
182 >  double vcom[3];
183 >  double p_local[9], p_global[9];
184 >  double theBox[3];
185 >  //double* tau;
186 >  int i, nMols;
187 >  Molecule* molecules;
188 >
189 >  nMols = entry_plug->n_mol;
190 >  molecules = entry_plug->molecules;
191 >  //tau = entry_plug->tau;
192 >
193 >  // use velocities of molecular centers of mass and molecular masses:
194 >  for (i=0; i < 9; i++) {    
195 >    p_local[i] = 0.0;
196 >    p_global[i] = 0.0;
197 >  }
198 >
199 >  for (i=0; i < nMols; i++) {
200 >    molmass = molecules[i].getCOMvel(vcom);
201 >
202 >    p_local[0] += molmass * (vcom[0] * vcom[0]);
203 >    p_local[1] += molmass * (vcom[0] * vcom[1]);
204 >    p_local[2] += molmass * (vcom[0] * vcom[2]);
205 >    p_local[3] += molmass * (vcom[1] * vcom[0]);
206 >    p_local[4] += molmass * (vcom[1] * vcom[1]);
207 >    p_local[5] += molmass * (vcom[1] * vcom[2]);
208 >    p_local[6] += molmass * (vcom[2] * vcom[0]);
209 >    p_local[7] += molmass * (vcom[2] * vcom[1]);
210 >    p_local[8] += molmass * (vcom[2] * vcom[2]);
211 >  }
212 >
213 >  // Get total for entire system from MPI.
214 >
215 > #ifdef IS_MPI
216 >  MPI_Allreduce(p_local,p_global,9,MPI_DOUBLE, MPI_SUM, MPI_COMM_WORLD);
217 > #else
218 >  for (i=0; i<9; i++) {
219 >    p_global[i] = p_local[i];
220 >  }
221 > #endif // is_mpi
222 >
223 >  volume = entry_plug->boxVol;
224 >
225 >  for(i=0; i<9; i++) {
226 >    press[i] = (p_global[i] - entry_plug->tau[i]*e_convert) / volume;
227 >  }
228   }
229  
230   void Thermo::velocitize() {

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