Changes in src/Dynamics/ForceAnnealing.hpp [4b2adf:0682c2]

File:

• src/Dynamics/ForceAnnealing.hpp (modified) (10 diffs)

src/Dynamics/ForceAnnealing.hpp

@@ -17 +17 @@
 #include <functional>
 #include <iterator>
+#include <math.h>
 
 #include <boost/bind.hpp>
@@ -167 +168 @@
   {
     double stepwidth = 0.;
-    if (_GradientDifference.NormSquared() > MYEPSILON)
+    if (_GradientDifference.Norm() > MYEPSILON)
       stepwidth = fabs(_PositionDifference.ScalarProduct(_GradientDifference))/
           _GradientDifference.NormSquared();
@@ -176 +177 @@
       stepwidth = currentDeltat;
     }
-    return stepwidth;
+    return std::min(1., stepwidth);
   }
 
@@ -200 +201 @@
         iter != AtomicForceManipulator<T>::atoms.end(); ++iter) {
       // atom's force vector gives steepest descent direction
-      const Vector currentPosition = (*iter)->getPositionAtStep(CurrentTimeStep);
-      const Vector currentGradient = (*iter)->getAtomicForceAtStep(CurrentTimeStep);
+      const Vector &currentPosition = (*iter)->getPositionAtStep(CurrentTimeStep);
+      const Vector &currentGradient = (*iter)->getAtomicForceAtStep(CurrentTimeStep);
       LOG(4, "DEBUG: currentPosition for atom #" << (*iter)->getId() << " is " << currentPosition);
       LOG(4, "DEBUG: currentGradient for atom #" << (*iter)->getId() << " is " << currentGradient);
@@ -248 +249 @@
   }
 
+  /** Performs Gradient optimization on a single atom using BarzilaiBorwein step width.
+   *
+   * \param _atom atom to anneal
+   * \param OldTimeStep old time step
+   * \param CurrentTimeStep current time step whose gradient we've just calculated
+   * \param TimeStepToSet time step to update (i.e. \f$ t + \Delta t \f$ in the sense of the velocity verlet)
+   */
+  void annealAtom_BarzilaiBorwein(
+      atom * const _atom,
+      const int &OldTimeStep,
+      const int &CurrentTimeStep,
+      const int &TimeStepToSet
+      )
+  {
+    // atom's force vector gives steepest descent direction
+    const Vector &oldPosition = _atom->getPositionAtStep(OldTimeStep);
+    const Vector &currentPosition = _atom->getPositionAtStep(CurrentTimeStep);
+    const Vector &oldGradient = _atom->getAtomicForceAtStep(OldTimeStep);
+    const Vector &currentGradient = _atom->getAtomicForceAtStep(CurrentTimeStep);
+    LOG(4, "DEBUG: oldPosition for atom #" << _atom->getId() << " is " << oldPosition);
+    LOG(4, "DEBUG: currentPosition for atom #" << _atom->getId() << " is " << currentPosition);
+    LOG(4, "DEBUG: oldGradient for atom #" << _atom->getId() << " is " << oldGradient);
+    LOG(4, "DEBUG: currentGradient for atom #" << _atom->getId() << " is " << currentGradient);
+//      LOG(4, "DEBUG: Force for atom #" << _atom->getId() << " is " << currentGradient);
+
+    // we use Barzilai-Borwein update with position reversed to get descent
+    const Vector PositionDifference = currentPosition - oldPosition;
+    const Vector GradientDifference = (currentGradient - oldGradient);
+    double stepwidth = getBarzilaiBorweinStepwidth(PositionDifference, GradientDifference);
+    Vector PositionUpdate = stepwidth * currentGradient;
+    LOG(3, "DEBUG: Update would be " << stepwidth << "*" << currentGradient << " = " << PositionUpdate);
+
+    // finally set new values
+    _atom->setPositionAtStep(TimeStepToSet, currentPosition + PositionUpdate);
+  }
+
   /** Performs Gradient optimization on the atoms using BarzilaiBorwein step width.
    *
    * \note this can only be called when there are at least two optimization
-   * time steps present, i.e. this must be preceeded by a simple anneal().
+   * time steps present, i.e. this must be preceded by a simple anneal().
    *
    * We assume that forces have just been calculated.
@@ -271 +308 @@
 
     Vector maxComponents;
-    bool deltat_decreased = false;
     for(typename AtomSetMixin<T>::iterator iter = AtomicForceManipulator<T>::atoms.begin();
         iter != AtomicForceManipulator<T>::atoms.end(); ++iter) {
-      // atom's force vector gives steepest descent direction
-      const Vector &oldPosition = (*iter)->getPositionAtStep(OldTimeStep);
-      const Vector &currentPosition = (*iter)->getPositionAtStep(CurrentTimeStep);
-      const Vector &oldGradient = (*iter)->getAtomicForceAtStep(OldTimeStep);
+
+      annealAtom_BarzilaiBorwein(*iter, OldTimeStep, CurrentTimeStep, _TimeStep);
+
+      // extract largest components for showing progress of annealing
       const Vector &currentGradient = (*iter)->getAtomicForceAtStep(CurrentTimeStep);
-      LOG(4, "DEBUG: oldPosition for atom #" << (*iter)->getId() << " is " << oldPosition);
-      LOG(4, "DEBUG: currentPosition for atom #" << (*iter)->getId() << " is " << currentPosition);
-      LOG(4, "DEBUG: oldGradient for atom #" << (*iter)->getId() << " is " << oldGradient);
-      LOG(4, "DEBUG: currentGradient for atom #" << (*iter)->getId() << " is " << currentGradient);
-//      LOG(4, "DEBUG: Force for atom #" << (*iter)->getId() << " is " << currentGradient);
-
-      // we use Barzilai-Borwein update with position reversed to get descent
-      const Vector PositionDifference = currentPosition - oldPosition;
-      const Vector GradientDifference = (currentGradient - oldGradient);
-      double stepwidth = getBarzilaiBorweinStepwidth(PositionDifference, GradientDifference);
-      Vector PositionUpdate = stepwidth * currentGradient;
-      LOG(3, "DEBUG: Update would be " << stepwidth << "*" << currentGradient << " = " << PositionUpdate);
-
-      // extract largest components for showing progress of annealing
       for(size_t i=0;i<NDIM;++i)
         maxComponents[i] = std::max(maxComponents[i], fabs(currentGradient[i]));
-
-//      // steps may go back and forth again (updates are of same magnitude but
-//      // have different sign: Check whether this is the case and one step with
-//      // deltat to interrupt this sequence
-//      if (!PositionDifference.IsZero())
-//        if ((PositionUpdate.ScalarProduct(PositionDifference) < 0)
-//            && (fabs(PositionUpdate.NormSquared()-PositionDifference.NormSquared()) < 1e-3)) {
-//          // for convergence we want a null sequence here, too
-//          if (!deltat_decreased) {
-//            deltat_decreased = true;
-//            currentDeltat = .5*currentDeltat;
-//          }
-//          LOG(2, "DEBUG: Upgrade in other direction: " << PositionUpdate
-//              << " > " << PositionDifference
-//              << ", using deltat: " << currentDeltat);
-//          PositionUpdate = currentDeltat * currentGradient;
-//      }
-
-      // finally set new values
-      (*iter)->setPositionAtStep(_TimeStep, currentPosition + PositionUpdate);
     }
 
     return maxComponents;
   }
+
+        /** Helper function to insert \a PositionUpdate into a map for every atom.
+         *
+         * \param _GatheredUpdates map of updates per atom
+         * \param _LargestUpdate_per_Atom map with the largest update per atom for checking
+         * \param _atomno key for map
+         * \param _PositionUpdate update to add
+         * \param _factor optional dampening factor
+         */
+        void updateInserter(
+            std::map<atomId_t, Vector> &_GatheredUpdates,
+            std::map<atomId_t, double> &_LargestUpdate_per_Atom,
+            const atomId_t _atomno,
+            const Vector &_PositionUpdate,
+            const double _factor = 1.
+            )
+        {
+          if (_GatheredUpdates.count(_atomno)) {
+            _GatheredUpdates[_atomno] += _factor*_PositionUpdate;
+            _LargestUpdate_per_Atom[_atomno] =
+                std::max(_LargestUpdate_per_Atom[_atomno], _factor*_PositionUpdate.Norm());
+          } else {
+            _GatheredUpdates.insert(
+                std::make_pair(
+                    _atomno,
+                    _factor*_PositionUpdate) );
+            _LargestUpdate_per_Atom.insert(
+                std::make_pair(
+                    _atomno,
+                    _PositionUpdate.Norm()) );
+          }
+        }
 
   /** Performs Gradient optimization on the bonds with BarzilaiBorwein stepwdith.
@@ -416 +450 @@
 
     std::map<atomId_t, Vector> GatheredUpdates; //!< gathers all updates which are applied at the end
+    std::map<atomId_t, double> LargestUpdate_per_Atom; //!< check whether updates cancelled each other
     for(typename AtomSetMixin<T>::iterator iter = AtomicForceManipulator<T>::atoms.begin();
         iter != AtomicForceManipulator<T>::atoms.end(); ++iter) {
@@ -434 +469 @@
       const Vector PositionDifference = currentPosition - oldPosition;
       const Vector GradientDifference = (currentGradient - oldGradient);
-      double stepwidth = 0.;
-      if (GradientDifference.Norm() > MYEPSILON)
-        stepwidth = fabs(PositionDifference.ScalarProduct(GradientDifference))/
-            GradientDifference.NormSquared();
-      if (fabs(stepwidth) < 1e-10) {
-        // dont' warn in first step, deltat usage normal
-        if (currentStep != 1)
-          ELOG(1, "INFO: Barzilai-Borwein stepwidth is zero, using deltat " << currentDeltat << " instead.");
-        stepwidth = currentDeltat;
-      }
+      double stepwidth = getBarzilaiBorweinStepwidth(PositionDifference, GradientDifference);
       Vector PositionUpdate = stepwidth * currentGradient;
+      // cap updates (if non-zero) at 0.2 angstroem. BB tends to overshoot.
+      for (size_t i=0;i<NDIM;++i)
+        if (fabs(PositionUpdate[i]) > MYEPSILON)
+          PositionUpdate[i] = std::min(0.2, fabs(PositionUpdate[i]))*PositionUpdate[i]/fabs(PositionUpdate[i]);
       LOG(3, "DEBUG: Update would be " << stepwidth << "*" << currentGradient << " = " << PositionUpdate);
 
-      /** for each atom, we imagine a plane at the position of the atom with
-       * its atomic gradient as the normal vector. We go through all its bonds
-       * and check on which side of the plane the bond is. This defines whether
-       * the bond is contracting (+) or expanding (-) with respect to this atom.
-       *
-       * A bond has two atoms, however. Hence, we do this for either atom and
-       * look at the combination: Is it in sum contracting or expanding given
-       * both projected_forces?
-       */
-
-      /** go through all bonds and check projected_forces and side of plane
-       * the idea is that if all bonds on one side are contracting ones or expanding,
-       * respectively, then we may shift not only the atom with respect to its
-       * gradient but also its neighbors (towards contraction or towards
-       * expansion depending on direction of gradient).
-       * if they are mixed on both sides of the plane, then we simply shift
-       * only the atom itself.
-       * if they are not mixed on either side, then we also only shift the
-       * atom, namely away from expanding and towards contracting bonds.
-       *
-       * We may get this information right away by looking at the projected_forces.
-       * They give the atomic gradient of either atom projected onto the BondVector
-       * with an additional weight in [0,1].
-       */
-
-      // sign encodes side of plane and also encodes contracting(-) or expanding(+)
-      typedef std::vector<int> sides_t;
-      typedef std::vector<int> types_t;
-      sides_t sides;
-      types_t types;
-      const BondList& ListOfBonds = walker.getListOfBonds();
-      for(BondList::const_iterator bonditer = ListOfBonds.begin();
-          bonditer != ListOfBonds.end(); ++bonditer) {
-        const bond::ptr &current_bond = *bonditer;
-
-        // BondVector goes from bond::rightatom to bond::leftatom
-        const size_t index = bv.getIndexForBond(current_bond);
-        std::vector<double> &forcelist = (&walker == current_bond->leftatom) ?
-            projected_forces[BondVectors::leftside] : projected_forces[BondVectors::rightside];
-        // note that projected_forces has sign such as to indicate whether
-        // atomic gradient wants bond to contract (-) or expand (+).
-        // This goes into sides: Minus side points away from gradient, plus side point
-        // towards gradient.
-        //
-        // the sum of both bond sides goes into types, depending on which is
-        // stronger if either wants a different thing
-        const double &temp = forcelist[index];
-        sides.push_back( -1.*temp/fabs(temp) ); // BondVectors has exactly opposite sign for sides decision
-        const double sum =
-            projected_forces[BondVectors::leftside][index]+projected_forces[BondVectors::rightside][index];
-        types.push_back( sum/fabs(sum) );
-        LOG(4, "DEBUG: Bond " << *current_bond << " is on side " << sides.back()
-            << " and has type " << types.back());
-      }
-//      /// check whether both conditions are compatible:
-//      // i.e. either we have ++/-- for all entries in sides and types
-//      // or we have +-/-+ for all entries
-//      // hence, multiplying and taking the sum and its absolute value
-//      // should be equal to the maximum number of entries
-//      sides_t results;
-//      std::transform(
-//          sides.begin(), sides.end(),
-//          types.begin(),
-//          std::back_inserter(results),
-//          std::multiplies<int>);
-//      int result = abs(std::accumulate(results.begin(), results.end(), 0, std::plus<int>));
-
-      std::vector<size_t> first_per_side(2, (size_t)-1); //!< mark down one representative from either side
-      std::vector< std::vector<int> > types_per_side(2); //!< gather all types on each side
-      types_t::const_iterator typesiter = types.begin();
-      for (sides_t::const_iterator sidesiter = sides.begin();
-          sidesiter != sides.end(); ++sidesiter, ++typesiter) {
-        const size_t index = (*sidesiter+1)/2;
-        types_per_side[index].push_back(*typesiter);
-        if (first_per_side[index] == (size_t)-1)
-          first_per_side[index] = std::distance(const_cast<const sides_t &>(sides).begin(), sidesiter);
-      }
-      LOG(4, "DEBUG: First on side minus is " << first_per_side[0] << ", and first on side plus is "
-          << first_per_side[1]);
-      //!> enumerate types per side with a little witching with the numbers to allow easy setting from types
-      enum whichtypes_t {
-        contracting=0,
-        unset=1,
-        expanding=2,
-        mixed
-      };
-      std::vector<int> typeside(2, unset);
-      for(size_t i=0;i<2;++i) {
-        for (std::vector<int>::const_iterator tpsiter = types_per_side[i].begin();
-            tpsiter != types_per_side[i].end(); ++tpsiter) {
-          if (typeside[i] == unset) {
-            typeside[i] = *tpsiter+1; //contracting(0) or expanding(2)
-          } else {
-            if (typeside[i] != (*tpsiter+1)) // no longer he same type
-              typeside[i] = mixed;
+      if (walker.getElementNo() != 1) {
+        /** for each atom, we imagine a plane at the position of the atom with
+         * its atomic gradient as the normal vector. We go through all its bonds
+         * and check on which side of the plane the bond is. This defines whether
+         * the bond is contracting (+) or expanding (-) with respect to this atom.
+         *
+         * A bond has two atoms, however. Hence, we do this for either atom and
+         * look at the combination: Is it in sum contracting or expanding given
+         * both projected_forces?
+         */
+
+        /** go through all bonds and check projected_forces and side of plane
+         * the idea is that if all bonds on one side are contracting ones or expanding,
+         * respectively, then we may shift not only the atom with respect to its
+         * gradient but also its neighbors (towards contraction or towards
+         * expansion depending on direction of gradient).
+         * if they are mixed on both sides of the plane, then we simply shift
+         * only the atom itself.
+         * if they are not mixed on either side, then we also only shift the
+         * atom, namely away from expanding and towards contracting bonds.
+         *
+         * We may get this information right away by looking at the projected_forces.
+         * They give the atomic gradient of either atom projected onto the BondVector
+         * with an additional weight in [0,1].
+         */
+
+        // sign encodes side of plane and also encodes contracting(-) or expanding(+)
+        typedef std::vector<int> sides_t;
+        typedef std::vector<int> types_t;
+        sides_t sides;
+        types_t types;
+        const BondList& ListOfBonds = walker.getListOfBonds();
+        for(BondList::const_iterator bonditer = ListOfBonds.begin();
+            bonditer != ListOfBonds.end(); ++bonditer) {
+          const bond::ptr &current_bond = *bonditer;
+
+          // BondVector goes from bond::rightatom to bond::leftatom
+          const size_t index = bv.getIndexForBond(current_bond);
+          std::vector<double> &forcelist = (&walker == current_bond->leftatom) ?
+              projected_forces[BondVectors::leftside] : projected_forces[BondVectors::rightside];
+          // note that projected_forces has sign such as to indicate whether
+          // atomic gradient wants bond to contract (-) or expand (+).
+          // This goes into sides: Minus side points away from gradient, plus side point
+          // towards gradient.
+          //
+          // the sum of both bond sides goes into types, depending on which is
+          // stronger if either wants a different thing
+          const double &temp = forcelist[index];
+          if (fabs(temp) < MYEPSILON)
+            sides.push_back(1);
+          else
+            sides.push_back( -1.*temp/fabs(temp) ); // BondVectors has exactly opposite sign for sides decision
+          ASSERT( (sides.back() == 1) || (sides.back() == -1),
+              "ForceAnnealing() - sides is not in {-1,1}.");
+          const double sum =
+              projected_forces[BondVectors::leftside][index]+projected_forces[BondVectors::rightside][index];
+          types.push_back( sum/fabs(sum) );
+          LOG(4, "DEBUG: Bond " << *current_bond << " is on side " << sides.back()
+              << " and has type " << types.back());
+        }
+  //      /// check whether both conditions are compatible:
+  //      // i.e. either we have ++/-- for all entries in sides and types
+  //      // or we have +-/-+ for all entries
+  //      // hence, multiplying and taking the sum and its absolute value
+  //      // should be equal to the maximum number of entries
+  //      sides_t results;
+  //      std::transform(
+  //          sides.begin(), sides.end(),
+  //          types.begin(),
+  //          std::back_inserter(results),
+  //          std::multiplies<int>);
+  //      int result = abs(std::accumulate(results.begin(), results.end(), 0, std::plus<int>));
+
+        std::vector<size_t> first_per_side(2, (size_t)-1); //!< mark down one representative from either side
+        std::vector< std::vector<int> > types_per_side(2); //!< gather all types on each side
+        types_t::const_iterator typesiter = types.begin();
+        for (sides_t::const_iterator sidesiter = sides.begin();
+            sidesiter != sides.end(); ++sidesiter, ++typesiter) {
+          const size_t index = (*sidesiter+1)/2;
+          types_per_side[index].push_back(*typesiter);
+          if (first_per_side[index] == (size_t)-1)
+            first_per_side[index] = std::distance(const_cast<const sides_t &>(sides).begin(), sidesiter);
+        }
+        LOG(4, "DEBUG: First on side minus is " << first_per_side[0] << ", and first on side plus is "
+            << first_per_side[1]);
+        //!> enumerate types per side with a little witching with the numbers to allow easy setting from types
+        enum whichtypes_t {
+          contracting=0,
+          unset=1,
+          expanding=2,
+          mixed
+        };
+        std::vector<int> typeside(2, unset);
+        for(size_t i=0;i<2;++i) {
+          for (std::vector<int>::const_iterator tpsiter = types_per_side[i].begin();
+              tpsiter != types_per_side[i].end(); ++tpsiter) {
+            if (typeside[i] == unset) {
+              typeside[i] = *tpsiter+1; //contracting(0) or expanding(2)
+            } else {
+              if (typeside[i] != (*tpsiter+1)) // no longer he same type
+                typeside[i] = mixed;
+            }
           }
         }
-      }
-      LOG(4, "DEBUG: Minus side is " << typeside[0] << " and plus side is " << typeside[1]);
-
-      typedef std::vector< std::pair<atomId_t, atomId_t> > RemovedEdges_t;
-      if ((typeside[0] != mixed) || (typeside[1] != mixed)) {
-        const size_t sideno = ((typeside[0] != mixed) && (typeside[0] != unset)) ? 0 : 1;
-        LOG(4, "DEBUG: Chosen side is " << sideno << " with type " << typeside[sideno]);
-        ASSERT( (typeside[sideno] == contracting) || (typeside[sideno] == expanding),
-            "annealWithBondGraph_BB() - chosen side is neither expanding nor contracting.");
-        // one side is not mixed, all bonds on one side are of same type
-        // hence, find out which bonds to exclude
-        const BondList& ListOfBonds = walker.getListOfBonds();
-
-        // sideno is away (0) or in direction (1) of gradient
-        // tpyes[first_per_side[sideno]] is either contracting (-1) or expanding (+1)
-        // : side (i), where (i) means which bonds we keep for the BFS, bonds
-        // on side (-i) are removed
-        // If all bonds on side away (0) want expansion (+1), move towards side with atom: side 1
-        // if all bonds side towards (1) want contraction (-1), move away side with atom : side -1
-
-        // unsure whether this or do nothing in the remaining cases:
-        // If all bonds on side toward (1) want expansion (+1), move away side with atom : side -1
-        //    (the reasoning is that the bond's other atom must have a stronger
-        //     gradient in the same direction and they push along atoms in
-        //     gradient direction: we don't want to interface with those.
-        //     Hence, move atoms along on away side
-        // if all bonds side away (0) want contraction (-1), move towards side with atom: side 1
-        //    (the reasoning is the same, don't interfere with update from
-        //     stronger gradient)
-        // hence, the decision is only based on sides once we have picked a side
-        // depending on all bonds associated with have same good type.
-        const double sign = sides[first_per_side[sideno]];
-        LOG(4, "DEBUG: Removing edges from side with sign " << sign);
-        BondList::const_iterator bonditer = ListOfBonds.begin();
-        RemovedEdges_t RemovedEdges;
-        for (sides_t::const_iterator sidesiter = sides.begin();
-            sidesiter != sides.end(); ++sidesiter, ++bonditer) {
-          if (*sidesiter == sign) {
-            // remove the edge
-            const bond::ptr &current_bond = *bonditer;
-            LOG(5, "DEBUG: Removing edge " << *current_bond);
-            RemovedEdges.push_back( std::make_pair(
-                current_bond->leftatom->getId(),
-                current_bond->rightatom->getId())
-            );
-#ifndef NDEBUG
-            const bool status =
-#endif
-                BGcreator.removeEdge(RemovedEdges.back());
-            ASSERT( status, "ForceAnnealing() - edge to found bond is not present?");
+        LOG(4, "DEBUG: Minus side is " << typeside[0] << " and plus side is " << typeside[1]);
+
+        typedef std::vector< std::pair<atomId_t, atomId_t> > RemovedEdges_t;
+        if ((typeside[0] != mixed) || (typeside[1] != mixed)) {
+          const size_t sideno = ((typeside[0] != mixed) && (typeside[0] != unset)) ? 0 : 1;
+          LOG(4, "DEBUG: Chosen side is " << sideno << " with type " << typeside[sideno]);
+          ASSERT( (typeside[sideno] == contracting) || (typeside[sideno] == expanding),
+              "annealWithBondGraph_BB() - chosen side is neither expanding nor contracting.");
+          // one side is not mixed, all bonds on one side are of same type
+          // hence, find out which bonds to exclude
+          const BondList& ListOfBonds = walker.getListOfBonds();
+
+          // sideno is away (0) or in direction (1) of gradient
+          // tpyes[first_per_side[sideno]] is either contracting (-1) or expanding (+1)
+          // : side (i), where (i) means which bonds we keep for the BFS, bonds
+          // on side (-i) are removed
+          // If all bonds on side away (0) want expansion (+1), move towards side with atom: side 1
+          // if all bonds side towards (1) want contraction (-1), move away side with atom : side -1
+
+          // unsure whether this or do nothing in the remaining cases:
+          // If all bonds on side toward (1) want expansion (+1), move away side with atom : side -1
+          //    (the reasoning is that the bond's other atom must have a stronger
+          //     gradient in the same direction and they push along atoms in
+          //     gradient direction: we don't want to interface with those.
+          //     Hence, move atoms along on away side
+          // if all bonds side away (0) want contraction (-1), move towards side with atom: side 1
+          //    (the reasoning is the same, don't interfere with update from
+          //     stronger gradient)
+          // hence, the decision is only based on sides once we have picked a side
+          // depending on all bonds associated with have same good type.
+
+          // away from gradient (minus) and contracting
+          // or towards gradient (plus) and expanding
+          // gather all on same side and remove
+          const double sign =
+              (sides[first_per_side[sideno]] == types[first_per_side[sideno]])
+              ? sides[first_per_side[sideno]] : -1.*sides[first_per_side[sideno]];
+
+          LOG(4, "DEBUG: Removing edges from side with sign " << sign);
+          BondList::const_iterator bonditer = ListOfBonds.begin();
+          RemovedEdges_t RemovedEdges;
+          for (sides_t::const_iterator sidesiter = sides.begin();
+              sidesiter != sides.end(); ++sidesiter, ++bonditer) {
+            if (*sidesiter == sign) {
+              // remove the edge
+              const bond::ptr &current_bond = *bonditer;
+              LOG(5, "DEBUG: Removing edge " << *current_bond);
+              RemovedEdges.push_back( std::make_pair(
+                  current_bond->leftatom->getId(),
+                  current_bond->rightatom->getId())
+              );
+  #ifndef NDEBUG
+              const bool status =
+  #endif
+                  BGcreator.removeEdge(RemovedEdges.back());
+              ASSERT( status, "ForceAnnealing() - edge to found bond is not present?");
+            }
           }
-        }
-        // perform limited-horizon BFS
-        BoostGraphHelpers::Nodeset_t bondside_set;
-        BreadthFirstSearchGatherer::distance_map_t distance_map;
-        bondside_set = NodeGatherer(walker.getId(), max_distance);
-        distance_map = NodeGatherer.getDistances();
-        std::sort(bondside_set.begin(), bondside_set.end());
-
-        // re-add edge
-        for (RemovedEdges_t::const_iterator edgeiter = RemovedEdges.begin();
-            edgeiter != RemovedEdges.end(); ++edgeiter)
-          BGcreator.addEdge(edgeiter->first, edgeiter->second);
-
-        // update position with dampening factor on the discovered bonds
-        for (BoostGraphHelpers::Nodeset_t::const_iterator setiter = bondside_set.begin();
-            setiter != bondside_set.end(); ++setiter) {
-          const BreadthFirstSearchGatherer::distance_map_t::const_iterator diter
-            = distance_map.find(*setiter);
-          ASSERT( diter != distance_map.end(),
-              "ForceAnnealing() - could not find distance to an atom.");
-          const double factor = pow(damping_factor, diter->second+1);
-          LOG(3, "DEBUG: Update for atom #" << *setiter << " will be "
-              << factor << "*" << PositionUpdate);
-          if (GatheredUpdates.count((*setiter))) {
-            GatheredUpdates[(*setiter)] += factor*PositionUpdate;
-          } else {
-            GatheredUpdates.insert(
-                std::make_pair(
-                    (*setiter),
-                    factor*PositionUpdate) );
+          // perform limited-horizon BFS
+          BoostGraphHelpers::Nodeset_t bondside_set;
+          BreadthFirstSearchGatherer::distance_map_t distance_map;
+          bondside_set = NodeGatherer(walker.getId(), max_distance);
+          distance_map = NodeGatherer.getDistances();
+          std::sort(bondside_set.begin(), bondside_set.end());
+
+          // re-add edge
+          for (RemovedEdges_t::const_iterator edgeiter = RemovedEdges.begin();
+              edgeiter != RemovedEdges.end(); ++edgeiter)
+            BGcreator.addEdge(edgeiter->first, edgeiter->second);
+
+          // update position with dampening factor on the discovered bonds
+          for (BoostGraphHelpers::Nodeset_t::const_iterator setiter = bondside_set.begin();
+              setiter != bondside_set.end(); ++setiter) {
+            const BreadthFirstSearchGatherer::distance_map_t::const_iterator diter
+              = distance_map.find(*setiter);
+            ASSERT( diter != distance_map.end(),
+                "ForceAnnealing() - could not find distance to an atom.");
+            const double factor = pow(damping_factor, diter->second+1);
+            LOG(3, "DEBUG: Update for atom #" << *setiter << " will be "
+                << factor << "*" << PositionUpdate);
+            updateInserter(GatheredUpdates, LargestUpdate_per_Atom, *setiter, PositionUpdate, factor);
           }
+        } else {
+          // simple atomic annealing, i.e. damping factor of 1
+          updateInserter(GatheredUpdates, LargestUpdate_per_Atom, walker.getId(), PositionUpdate);
         }
       } else {
-        // simple atomic annealing, i.e. damping factor of 1
-        LOG(3, "DEBUG: Update for atom #" << walker.getId() << " will be " << PositionUpdate);
-        GatheredUpdates.insert(
-            std::make_pair(
-                walker.getId(),
-                PositionUpdate) );
+        // hydrogens (are light-weighted and therefore) are always updated normally
+        LOG(3, "DEBUG: Update for hydrogen #" << walker.getId() << " will be " << PositionUpdate);
+        updateInserter(GatheredUpdates, LargestUpdate_per_Atom, walker.getId(), PositionUpdate);
       }
     }
@@ -641 +678 @@
       atom &walker = *(*iter);
       // extract largest components for showing progress of annealing
-      const Vector currentGradient = walker.getAtomicForceAtStep(CurrentTimeStep);
+      const Vector &currentGradient = walker.getAtomicForceAtStep(CurrentTimeStep);
       for(size_t i=0;i<NDIM;++i)
         maxComponents[i] = std::max(maxComponents[i], fabs(currentGradient[i]));
@@ -670 +707 @@
       for (size_t i=0;i<NDIM;++i)
         LargestUpdate[i] = std::max(LargestUpdate[i], fabs(update[i]));
-      walker->setPositionAtStep(_TimeStep,
-          walker->getPositionAtStep(CurrentTimeStep) + update); // - CommonTranslation);
+
+      std::map<atomId_t, double>::const_iterator largestiter = LargestUpdate_per_Atom.find(atomid);
+      ASSERT( largestiter != LargestUpdate_per_Atom.end(),
+          "ForceAnnealing() - walker with id "+toString(atomid)+" not in LargestUpdates.");
+      // if we had large updates but their sum is very small
+      if (update.Norm()/largestiter->second > MYEPSILON) {
+        walker->setPositionAtStep(_TimeStep,
+            walker->getPositionAtStep(CurrentTimeStep) + update); // - CommonTranslation);
+      } else {
+        // then recalc update with simple anneal
+        LOG(2, "WARNING: Updates on atom " << *iter << " cancel themselves, performing simple anneal step.");
+        annealAtom_BarzilaiBorwein(walker, OldTimeStep, CurrentTimeStep, _TimeStep);
+      }
     }
     LOG(1, "STATUS: Largest absolute update components are " << LargestUpdate);