double OrientationSphere::compute(){
// Make sure derivatives for central atom are only calculated once
VectorMultiColvar* vv = dynamic_cast<VectorMultiColvar*>( getBaseMultiColvar(0) );
vv->firstcall=true;
weightHasDerivatives=true; // The weight has no derivatives really
double sw, value=0, denom=0, dot, f_dot, dot_df, dfunc; Vector distance;
getVectorForBaseTask(0, catom_orient );
for(unsigned i=1;i<getNAtoms();++i){
distance=getSeparation( getPositionOfCentralAtom(0), getPositionOfCentralAtom(i) );
sw = switchingFunction.calculateSqr( distance.modulo2(), dfunc );
if( sw>=getTolerance() ){
getVectorForBaseTask( i, this_orient );
// Calculate the dot product wrt to this position
dot=0; for(unsigned k=0;k<catom_orient.size();++k) dot+=catom_orient[k]*this_orient[k];
f_dot = transformDotProduct( dot, dot_df );
// N.B. We are assuming here that the imaginary part of the dot product is zero
for(unsigned k=0;k<catom_orient.size();++k){
this_orient[k]*=sw*dot_df; catom_der[k]=sw*dot_df*catom_orient[k];
}
// Set the derivatives wrt of the numerator
addOrientationDerivatives( 0, this_orient );
addOrientationDerivatives( i, catom_der );
addCentralAtomsDerivatives( 0, 0, f_dot*(-dfunc)*distance );
addCentralAtomsDerivatives( i, 0, f_dot*(dfunc)*distance );
addBoxDerivatives( f_dot*(-dfunc)*Tensor(distance,distance) );
value += sw*f_dot;
// Set the derivatives wrt to the numerator
addCentralAtomsDerivatives( 0, 1, (-dfunc)*distance );
addCentralAtomsDerivatives( i, 1, (dfunc)*distance );
addBoxDerivativesOfWeight( (-dfunc)*Tensor(distance,distance) );
denom += sw;
}
}
// Now divide everything
unsigned nder = getNumberOfDerivatives();
for(unsigned i=0;i<nder;++i){
setElementDerivative( i, getElementDerivative(i)/denom - (value*getElementDerivative(nder+i))/(denom*denom) );
setElementDerivative( nder + i, 0.0 );
}
weightHasDerivatives=false; // Weight has no derivatives we just use the holder for weight to store some stuff
return value / denom;
}
double OrientationSphere::compute( const unsigned& tindex, multicolvar::AtomValuePack& myatoms ) const {
// Make sure derivatives for central atom are only calculated once
VectorMultiColvar* vv = dynamic_cast<VectorMultiColvar*>( getBaseMultiColvar(0) );
vv->firstcall=true;
double d2, sw, value=0, denom=0, dot, f_dot, dot_df, dfunc;
unsigned ncomponents=getBaseMultiColvar(0)->getNumberOfQuantities();
unsigned nder=myatoms.getNumberOfDerivatives();
std::vector<double> catom_orient( ncomponents ), this_orient( ncomponents ), catom_der( ncomponents );
Vector catom_pos = myatoms.getPosition(0);
getVectorForTask( myatoms.getIndex(0), true, catom_orient );
multicolvar::CatomPack atom0; MultiValue myder0(0,0), myder1(0,0);
if( !doNotCalculateDerivatives() ){
myder0.resize( ncomponents,nder ); myder1.resize(ncomponents,nder);
atom0=getCentralAtomPackFromInput( myatoms.getIndex(0) );
getVectorDerivatives( myatoms.getIndex(0), true, myder0 );
}
for(unsigned i=1;i<myatoms.getNumberOfAtoms();++i){
Vector& distance=myatoms.getPosition(i);
if ( (d2=distance[0]*distance[0])<rcut2 &&
(d2+=distance[1]*distance[1])<rcut2 &&
(d2+=distance[2]*distance[2])<rcut2) {
sw = switchingFunction.calculateSqr( d2, dfunc );
getVectorForTask( myatoms.getIndex(i), true, this_orient );
// Calculate the dot product wrt to this position
dot=0; for(unsigned k=2;k<catom_orient.size();++k) dot+=catom_orient[k]*this_orient[k];
f_dot = transformDotProduct( dot, dot_df );
if( !doNotCalculateDerivatives() ){
// N.B. We are assuming here that the imaginary part of the dot product is zero
for(unsigned k=2;k<catom_orient.size();++k){
this_orient[k]*=sw*dot_df; catom_der[k]=sw*dot_df*catom_orient[k];
}
getVectorDerivatives( myatoms.getIndex(i), true, myder1 );
mergeVectorDerivatives( 1, 2, this_orient.size(), myatoms.getIndex(0), this_orient, myder0, myatoms );
mergeVectorDerivatives( 1, 2, catom_der.size(), myatoms.getIndex(i), catom_der, myder1, myatoms );
myatoms.addComDerivatives( 1, f_dot*(-dfunc)*distance, atom0 );
addAtomDerivatives( 1, i, f_dot*(dfunc)*distance, myatoms );
myatoms.addBoxDerivatives( 1, (-dfunc)*f_dot*Tensor(distance,distance) );
myder1.clearAll();
myatoms.addComDerivatives( -1, (-dfunc)*distance, atom0 );
addAtomDerivatives( -1, i, (dfunc)*distance, myatoms );
myatoms.addTemporyBoxDerivatives( (-dfunc)*Tensor(distance,distance) );
}
value += sw*f_dot;
denom += sw;
}
}
double rdenom, df2, pref=calculateCoordinationPrefactor( denom, df2 );
if( fabs(denom)>epsilon ){ rdenom = 1.0 / denom; }
else { plumed_assert(fabs(value)<epsilon); rdenom=1.0; }
// Now divide everything
double rdenom2=rdenom*rdenom;
updateActiveAtoms( myatoms ); MultiValue& myvals=myatoms.getUnderlyingMultiValue();
for(unsigned i=0;i<myvals.getNumberActive();++i){
unsigned ider=myvals.getActiveIndex(i);
double dgd=myvals.getTemporyDerivative(ider);
myvals.setDerivative( 1, ider, rdenom*(pref*myvals.getDerivative(1,ider)+value*df2*dgd) - (value*pref*dgd)*rdenom2 );
}
return pref*rdenom*value;
}
