NAME

       sc::FinDispMolecularHessian - Computes the molecular hessian by finite displacements of
       gradients.

SYNOPSIS

       #include <fdhess.h>

       Inherits sc::MolecularHessian.

   Public Member Functions
       FinDispMolecularHessian (const Ref< MolecularEnergy > &)
       FinDispMolecularHessian (const Ref< KeyVal > &)
           The FinDispMolecularHessian KeyVal constructor is used to generate a
           FinDispMolecularHessian object from the input.
       FinDispMolecularHessian (StateIn &)
       void save_data_state (StateOut &)
           Save the base classes (with save_data_state) and the members in the same order that
           the StateIn CTOR initializes them.
       RefSymmSCMatrix compute_hessian_from_gradients ()
           These members are used to compute a cartesian hessian from gradients at finite
           displacements.
       int ndisplace () const
       int ndisplacements_done () const
       RefSCMatrix displacements (int irrep) const
       void displace (int disp)
       void original_geometry ()
       void set_gradient (int disp, const RefSCVector &grad)
       void checkpoint_displacements (StateOut &)
       void restore_displacements (StateIn &)
       RefSymmSCMatrix cartesian_hessian ()
           This returns the cartesian hessian.
       void set_checkpoint (int c)
           Set checkpoint option.
       int checkpoint () const
           Return the current value of the checkpoint option.
       void set_energy (const Ref< MolecularEnergy > &energy)
           Some MolecularHessian specializations require a molecular energy object.
       MolecularEnergy * energy () const
           This returns a MolecularEnergy object, if used by this specialization.
       Ref< SCMatrixKit > matrixkit () const
       RefSCDimension d3natom () const

   Protected Member Functions
       void get_disp (int disp, int &irrep, int &index, double &coef)
       void do_hess_for_irrep (int irrep, const RefSymmSCMatrix &dhessian, const RefSymmSCMatrix
           &xhessian)
       void init ()
       void restart ()

   Protected Attributes
       Ref< MolecularEnergy > mole_
       Ref< PointGroup > displacement_point_group_
       Ref< PointGroup > original_point_group_
       RefSCVector original_geometry_
       double disp_
       double accuracy_
       int ndisp_
       int nirrep_
       int restart_
       char * restart_file_
       int checkpoint_
       char * checkpoint_file_
       int only_totally_symmetric_
       int eliminate_cubic_terms_
       int do_null_displacement_
       int debug_
       RefSCMatrix symbasis_
       RefSCVector * gradients_

   Additional Inherited Members

Detailed Description

       Computes the molecular hessian by finite displacements of gradients.

       This will use the minimum number of displacements, each in the highest possible point
       group.

Constructor & Destructor Documentation

   sc::FinDispMolecularHessian::FinDispMolecularHessian (const Ref< KeyVal > &)
       The FinDispMolecularHessian KeyVal constructor is used to generate a
       FinDispMolecularHessian object from the input. It reads the keywords below.

       KeywordTypeDefaultDescription

       energyMolecularEnergynoneThis gives an object which will be used to compute the gradients
       needed to form the hessian. If this is not specified, the object using
       FinDispMolecularHessian will, in some cases, fill it in appropriately. However, even in
       these cases, it may be desirable to specify this keyword. For example, this could be used
       in an optimization to compute frequencies using a lower level of theory.

       debugbooleanfalseIf true, print out debugging information.

       point_groupPointGroupnoneThe point group to use for generating the displacements.

       restartbooleantrueIf true, and a checkpoint file exists, restart from that file.

       restart_filestring basename.ckpt.hessThe name of the file where checkpoint information is
       written to or read from.

       checkpointbooleantrueIf true, checkpoint intermediate data.

       only_totally_symmetricbooleanfalse If true, only follow totally symmetric displacments.
       The hessian will not be complete, but it has enough information to use it in a geometry
       optimization.

       eliminate_cubic_termsbooleantrueIf true, then cubic terms will be eliminated. This
       requires that two displacements are done for each totally symmetric coordinate, rather
       than one. Setting this to false will reduce the accuracy, but the results will still
       probably be accurate enough for a geometry optimization.

       do_null_displacementbooleantrueRun the calculation at the given geometry as well.

       displacementdouble1.0e-2The size of the displacement in Bohr.

       gradient_accuracydoubledisplacement / 1000The accuracy to which the gradients will be
       computed.

Member Function Documentation

   RefSymmSCMatrix sc::FinDispMolecularHessian::cartesian_hessian () [virtual]
       This returns the cartesian hessian. If it has not yet been computed, it will be computed
       by finite displacements.

       Implements sc::MolecularHessian.

   MolecularEnergy* sc::FinDispMolecularHessian::energy () const [virtual]
       This returns a MolecularEnergy object, if used by this specialization. Otherwise null is
       returned.

       Reimplemented from sc::MolecularHessian.

   void sc::FinDispMolecularHessian::save_data_state (StateOut &) [virtual]
       Save the base classes (with save_data_state) and the members in the same order that the
       StateIn CTOR initializes them. This must be implemented by the derived class if the class
       has data.

       Reimplemented from sc::SavableState.

   void sc::FinDispMolecularHessian::set_energy (const Ref< MolecularEnergy > & energy) [virtual]
       Some MolecularHessian specializations require a molecular energy object. The default
       implementations of this ignores the argument.

       Reimplemented from sc::MolecularHessian.

Author

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