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#include <cmath> |
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#include "Atom.hpp" |
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#include "SRI.hpp" |
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#include "AbstractClasses.hpp" |
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#include "SimInfo.hpp" |
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#include "ForceFields.hpp" |
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#include "Thermo.hpp" |
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#include "ReadWrite.hpp" |
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#include "Integrator.hpp" |
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#include "simError.h" |
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|
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|
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// Basic isotropic thermostating and barostating via the Melchionna |
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// modification of the Hoover algorithm: |
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// |
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// Melchionna, S., Ciccotti, G., and Holian, B. L., 1993, |
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// Molec. Phys., 78, 533. |
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// |
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// and |
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// |
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// Hoover, W. G., 1986, Phys. Rev. A, 34, 2499. |
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|
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NPTi::NPTi ( SimInfo *theInfo, ForceFields* the_ff): |
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Integrator( theInfo, the_ff ) |
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{ |
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chi = 0.0; |
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eta = 0.0; |
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have_tau_thermostat = 0; |
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have_tau_barostat = 0; |
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have_target_temp = 0; |
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have_target_pressure = 0; |
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} |
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|
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void NPTi::moveA() { |
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|
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int i, j; |
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DirectionalAtom* dAtom; |
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double Tb[3], ji[3]; |
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double A[3][3], I[3][3]; |
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double angle, mass; |
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double vel[3], pos[3], frc[3]; |
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|
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double rj[3]; |
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double instaTemp, instaPress, instaVol; |
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double tt2, tb2, scaleFactor; |
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|
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tt2 = tauThermostat * tauThermostat; |
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tb2 = tauBarostat * tauBarostat; |
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|
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instaTemp = tStats->getTemperature(); |
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instaPress = tStats->getPressure(); |
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instaVol = tStats->getVolume(); |
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|
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// first evolve chi a half step |
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|
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chi += dt2 * ( instaTemp / targetTemp - 1.0) / tt2; |
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eta += dt2 * ( instaVol * (instaPress - targetPressure) / |
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(p_convert*NkBT*tb2)); |
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|
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for( i=0; i<nAtoms; i++ ){ |
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atoms[i]->getVel( vel ); |
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atoms[i]->getPos( pos ); |
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atoms[i]->getFrc( frc ); |
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|
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mass = atoms[i]->getMass(); |
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|
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for (j=0; j < 3; j++) { |
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vel[j] += dt2 * ((frc[j] / mass ) * eConvert - vel[j]*(chi+eta)); |
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rj[j] = pos[j]; |
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} |
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|
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atoms[i]->setVel( vel ); |
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|
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info->wrapVector(rj); |
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|
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for (j = 0; j < 3; j++) |
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pos[j] += dt * (vel[j] + eta*rj[j]); |
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|
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atoms[i]->setPos( pos ); |
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|
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if( atoms[i]->isDirectional() ){ |
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|
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dAtom = (DirectionalAtom *)atoms[i]; |
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|
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// get and convert the torque to body frame |
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|
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dAtom->getTrq( Tb ); |
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dAtom->lab2Body( Tb ); |
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|
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// get the angular momentum, and propagate a half step |
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|
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dAtom->getJ( ji ); |
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|
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for (j=0; j < 3; j++) |
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ji[j] += dt2 * (Tb[j] * eConvert - ji[j]*chi); |
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|
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// use the angular velocities to propagate the rotation matrix a |
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// full time step |
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|
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dAtom->getA(A); |
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dAtom->getI(I); |
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|
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// rotate about the x-axis |
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angle = dt2 * ji[0] / I[0][0]; |
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this->rotate( 1, 2, angle, ji, A ); |
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|
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// rotate about the y-axis |
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angle = dt2 * ji[1] / I[1][1]; |
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this->rotate( 2, 0, angle, ji, A ); |
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|
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// rotate about the z-axis |
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angle = dt * ji[2] / I[2][2]; |
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this->rotate( 0, 1, angle, ji, A); |
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|
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// rotate about the y-axis |
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angle = dt2 * ji[1] / I[1][1]; |
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this->rotate( 2, 0, angle, ji, A ); |
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|
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// rotate about the x-axis |
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angle = dt2 * ji[0] / I[0][0]; |
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this->rotate( 1, 2, angle, ji, A ); |
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|
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dAtom->setJ( ji ); |
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dAtom->setA( A ); |
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} |
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|
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} |
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|
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// Scale the box after all the positions have been moved: |
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|
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scaleFactor = exp(dt*eta); |
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|
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if ((scaleFactor > 1.1) || (scaleFactor < 0.9)) { |
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sprintf( painCave.errMsg, |
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"NPTi error: Attempting a Box scaling of more than 10 percent" |
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" check your tauBarostat, as it is probably too small!\n" |
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" eta = %lf, scaleFactor = %lf\n", eta, scaleFactor |
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); |
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painCave.isFatal = 1; |
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simError(); |
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} else { |
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info->scaleBox(exp(dt*eta)); |
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} |
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|
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} |
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|
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void NPTi::moveB( void ){ |
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|
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int i, j; |
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DirectionalAtom* dAtom; |
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double Tb[3], ji[3]; |
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double vel[3], frc[3]; |
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double mass; |
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|
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double instaTemp, instaPress, instaVol; |
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double tt2, tb2; |
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|
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tt2 = tauThermostat * tauThermostat; |
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tb2 = tauBarostat * tauBarostat; |
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|
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instaTemp = tStats->getTemperature(); |
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instaPress = tStats->getPressure(); |
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instaVol = tStats->getVolume(); |
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|
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chi += dt2 * ( instaTemp / targetTemp - 1.0) / tt2; |
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eta += dt2 * ( instaVol * (instaPress - targetPressure) / |
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(p_convert*NkBT*tb2)); |
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|
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for( i=0; i<nAtoms; i++ ){ |
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|
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atoms[i]->getVel( vel ); |
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atoms[i]->getFrc( frc ); |
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|
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mass = atoms[i]->getMass(); |
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|
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// velocity half step |
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for (j=0; j < 3; j++) |
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vel[j] += dt2 * ((frc[j] / mass ) * eConvert - vel[j]*(chi+eta)); |
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|
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atoms[i]->setVel( vel ); |
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|
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if( atoms[i]->isDirectional() ){ |
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|
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dAtom = (DirectionalAtom *)atoms[i]; |
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|
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// get and convert the torque to body frame |
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|
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dAtom->getTrq( Tb ); |
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dAtom->lab2Body( Tb ); |
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|
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// get the angular momentum, and propagate a half step |
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|
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dAtom->getJ( ji ); |
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|
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for (j=0; j < 3; j++) |
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ji[j] += dt2 * (Tb[j] * eConvert - ji[j]*chi); |
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|
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dAtom->setJ( ji ); |
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} |
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} |
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} |
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|
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int NPTi::readyCheck() { |
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|
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// First check to see if we have a target temperature. |
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// Not having one is fatal. |
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|
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if (!have_target_temp) { |
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sprintf( painCave.errMsg, |
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"NPTi error: You can't use the NPTi integrator\n" |
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" without a targetTemp!\n" |
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); |
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painCave.isFatal = 1; |
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simError(); |
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return -1; |
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} |
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|
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if (!have_target_pressure) { |
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sprintf( painCave.errMsg, |
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"NPTi error: You can't use the NPTi integrator\n" |
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" without a targetPressure!\n" |
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); |
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painCave.isFatal = 1; |
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simError(); |
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return -1; |
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} |
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|
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// We must set tauThermostat. |
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|
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if (!have_tau_thermostat) { |
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sprintf( painCave.errMsg, |
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"NPTi error: If you use the NPTi\n" |
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" integrator, you must set tauThermostat.\n"); |
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painCave.isFatal = 1; |
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simError(); |
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return -1; |
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} |
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|
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// We must set tauBarostat. |
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|
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if (!have_tau_barostat) { |
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sprintf( painCave.errMsg, |
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"NPTi error: If you use the NPTi\n" |
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" integrator, you must set tauBarostat.\n"); |
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painCave.isFatal = 1; |
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simError(); |
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return -1; |
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} |
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|
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// We need NkBT a lot, so just set it here: |
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|
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NkBT = (double)info->ndf * kB * targetTemp; |
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|
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return 1; |
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} |
