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root/OpenMD/branches/development/src/nonbonded/GB.cpp
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Comparing branches/development/src/nonbonded/GB.cpp (file contents):
Revision 1668 by gezelter, Fri Jan 6 19:03:05 2012 UTC vs.
Revision 1674 by gezelter, Thu Feb 16 15:59:20 2012 UTC

# Line 223 | Line 223 | namespace OpenMD {
223          dw2 = 1.0;
224        }
225                        
226 <      GBInteractionData mixer;        
226 >      GBInteractionData mixer1, mixer2;    
227        
228        //  Cleaver paper uses sqrt of squares to get sigma0 for
229        //  mixed interactions.
230              
231 <      mixer.sigma0 = sqrt(d1*d1 + d2*d2);
232 <      mixer.xa2 = (l1*l1 - d1*d1)/(l1*l1 + d2*d2);
233 <      mixer.xai2 = (l2*l2 - d2*d2)/(l2*l2 + d1*d1);
234 <      mixer.x2 = (l1*l1 - d1*d1) * (l2*l2 - d2*d2) /
231 >      mixer1.sigma0 = sqrt(d1*d1 + d2*d2);
232 >      mixer1.xa2 = (l1*l1 - d1*d1)/(l1*l1 + d2*d2);
233 >      mixer1.xai2 = (l2*l2 - d2*d2)/(l2*l2 + d1*d1);
234 >      mixer1.x2 = (l1*l1 - d1*d1) * (l2*l2 - d2*d2) /
235          ((l2*l2 + d1*d1) * (l1*l1 + d2*d2));
236 +
237 +      mixer2.sigma0 = mixer1.sigma0;
238 +      // xa2 and xai2 for j-i pairs are reversed from the same i-j pairing.
239 +      // Swapping the particles reverses the anisotropy parameters:
240 +      mixer2.xa2 = mixer1.xai2;
241 +      mixer2.xai2 = mixer1.xa2;
242 +      mixer2.x2 = mixer1.x2;
243  
244        // assumed LB mixing rules for now:
245  
246 <      mixer.dw = 0.5 * (dw1 + dw2);
247 <      mixer.eps0 = sqrt(e1 * e2);
246 >      mixer1.dw = 0.5 * (dw1 + dw2);
247 >      mixer1.eps0 = sqrt(e1 * e2);
248 >
249 >      mixer2.dw = mixer1.dw;
250 >      mixer2.eps0 = mixer1.eps0;
251        
252        RealType er = sqrt(er1 * er2);
253        RealType ermu = pow(er, (RealType(1.0) / mu_));
254        RealType xp = (1.0 - ermu) / (1.0 + ermu);
255        RealType ap2 = 1.0 / (1.0 + ermu);
256        
257 <      mixer.xp2 = xp * xp;
258 <      mixer.xpap2 = xp * ap2;
259 <      mixer.xpapi2 = xp / ap2;
257 >      mixer1.xp2 = xp * xp;
258 >      mixer1.xpap2 = xp * ap2;
259 >      mixer1.xpapi2 = xp / ap2;
260  
261 <      cerr << "mixer" << er1 << " " << er2 << " " << mu_ << " " << ermu << " " << xp <<" " << ap2 << "\n";
261 >      mixer2.xp2 = mixer1.xp2;
262 >      mixer2.xpap2 = mixer1.xpap2;
263 >      mixer2.xpapi2 = mixer1.xpapi2;
264  
265        // only add this pairing if at least one of the atoms is a Gay-Berne atom
266  
# Line 258 | Line 270 | namespace OpenMD {
270          key1 = make_pair(atomType, atype2);
271          key2 = make_pair(atype2, atomType);
272          
273 <        MixingMap[key1] = mixer;
273 >        MixingMap[key1] = mixer1;
274          if (key2 != key1) {
275 <          MixingMap[key2] = mixer;
275 >          MixingMap[key2] = mixer2;
276          }
277        }
278      }      
# Line 309 | Line 321 | namespace OpenMD {
321      else
322        g = dot(ul1, ul2);
323  
312    cerr << "in GB, d = " << *(idat.d) << "\n";
313    cerr << "abg = " << a << " " << b << " " << g <<"\n";
314
324      RealType au = a / *(idat.rij);
325      RealType bu = b / *(idat.rij);
326      
# Line 321 | Line 330 | namespace OpenMD {
330      
331      RealType H  = (xa2 * au2 + xai2 * bu2 - 2.0*x2*au*bu*g)  / (1.0 - x2*g2);
332      RealType Hp = (xpap2*au2 + xpapi2*bu2 - 2.0*xp2*au*bu*g) / (1.0 - xp2*g2);
324    cerr << "xa2, xai2 " << xa2 << " " << xai2 << "\n";
325    cerr << "xpap2, xpapi2 " << xpap2 << " " << xpapi2 << "\n";
326    cerr << "H Hp = " << H <<  " " << Hp << "\n";
333  
334      RealType sigma = sigma0 / sqrt(1.0 - H);
335      RealType e1 = 1.0 / sqrt(1.0 - x2*g2);
336      RealType e2 = 1.0 - Hp;
337      RealType eps = eps0 * pow(e1,nu_) * pow(e2,mu_);
332    cerr << "eps = " << eps0 << " " << e1 << " " << nu_ << " " << e2 << " " << mu_ << "\n";
338      RealType BigR = dw*sigma0 / (*(idat.rij) - sigma + dw*sigma0);
339      
340      RealType R3 = BigR*BigR*BigR;
# Line 340 | Line 345 | namespace OpenMD {
345  
346      RealType U = *(idat.vdwMult) * 4.0 * eps * (R12 - R6);
347  
343    cerr << "R12, R6, eps = " << R12 << " " << R6 << " " << eps << " " <<  *(idat.vdwMult) << "\n";
344
348      RealType s3 = sigma*sigma*sigma;
349      RealType s03 = sigma0*sigma0*sigma0;
350  
# Line 365 | Line 368 | namespace OpenMD {
368        (1.0 - xp2 * g2) / e2 + 8.0 * eps * s3 * (3.0 * R7 - 6.0 * R13) *
369        (x2 * au * bu - H * x2 * g) / (1.0 - x2 * g2) / (dw * s03);
370  
368    cerr << pref1 << " " << pref2 << " " << dUdr <<" " << dUda << " " << dUdb << dUdg << "\n";
369
371      Vector3d rhat = *(idat.d) / *(idat.rij);  
372      Vector3d rxu1 = cross(*(idat.d), ul1);
373      Vector3d rxu2 = cross(*(idat.d), ul2);
374      Vector3d uxu = cross(ul1, ul2);
375  
375    cerr << "U = " << U << "\n";
376    cerr << "f1 = " << dUdr * rhat + dUda * ul1 + dUdb * ul2 << "\n";
377    cerr << "t1 = " << dUda * rxu1 - dUdg * uxu << "\n";
378    cerr << "t2 = " << dUdb * rxu2 - dUdg * uxu << "\n";
379
380    
376      (*(idat.pot))[VANDERWAALS_FAMILY] += U *  *(idat.sw);
377      *(idat.f1) += dUdr * rhat + dUda * ul1 + dUdb * ul2;    
378      *(idat.t1) += dUda * rxu1 - dUdg * uxu;
379 <    *(idat.t2) += dUdb * rxu2 - dUdg * uxu;
379 >    *(idat.t2) += dUdb * rxu2 + dUdg * uxu;
380      *(idat.vpair) += U * *(idat.sw);
381  
382      return;

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