.TH "sc::FinDispMolecularHessian" 3 "Sun Oct 4 2020" "Version 2.3.1" "MPQC" \" -*- nroff -*-
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.SH NAME
sc::FinDispMolecularHessian \- Computes the molecular hessian by finite displacements of gradients\&.  

.SH SYNOPSIS
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.PP
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\fC#include <fdhess\&.h>\fP
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Inherits \fBsc::MolecularHessian\fP\&.
.SS "Public Member Functions"

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.RI "\fBFinDispMolecularHessian\fP (const \fBRef\fP< \fBMolecularEnergy\fP > &)"
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.RI "\fBFinDispMolecularHessian\fP (const \fBRef\fP< \fBKeyVal\fP > &)"
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.RI "The \fBFinDispMolecularHessian\fP \fBKeyVal\fP constructor is used to generate a \fBFinDispMolecularHessian\fP object from the input\&. "
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.RI "\fBFinDispMolecularHessian\fP (\fBStateIn\fP &)"
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.RI "void \fBsave_data_state\fP (\fBStateOut\fP &)"
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.RI "Save the base classes (with save_data_state) and the members in the same order that the \fBStateIn\fP CTOR initializes them\&. "
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.RI "\fBRefSymmSCMatrix\fP \fBcompute_hessian_from_gradients\fP ()"
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.RI "These members are used to compute a cartesian hessian from gradients at finite displacements\&. "
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.RI "int \fBndisplace\fP () const"
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.RI "int \fBndisplacements_done\fP () const"
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.RI "\fBRefSCMatrix\fP \fBdisplacements\fP (int irrep) const"
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.RI "void \fBdisplace\fP (int disp)"
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.RI "void \fBoriginal_geometry\fP ()"
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.RI "void \fBset_gradient\fP (int disp, const \fBRefSCVector\fP &grad)"
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.RI "void \fBcheckpoint_displacements\fP (\fBStateOut\fP &)"
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.RI "void \fBrestore_displacements\fP (\fBStateIn\fP &)"
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.RI "\fBRefSymmSCMatrix\fP \fBcartesian_hessian\fP ()"
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.RI "This returns the cartesian hessian\&. "
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.RI "void \fBset_checkpoint\fP (int c)"
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.RI "Set checkpoint option\&. "
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.RI "int \fBcheckpoint\fP () const"
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.RI "Return the current value of the checkpoint option\&. "
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.RI "void \fBset_energy\fP (const \fBRef\fP< \fBMolecularEnergy\fP > &\fBenergy\fP)"
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.RI "Some \fBMolecularHessian\fP specializations require a molecular energy object\&. "
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.RI "\fBMolecularEnergy\fP * \fBenergy\fP () const"
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.RI "This returns a \fBMolecularEnergy\fP object, if used by this specialization\&. "
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.RI "\fBRef\fP< \fBSCMatrixKit\fP > \fBmatrixkit\fP () const"
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.RI "\fBRefSCDimension\fP \fBd3natom\fP () const"
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.SS "Protected Member Functions"

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.RI "void \fBget_disp\fP (int disp, int &irrep, int &index, double &coef)"
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.RI "void \fBdo_hess_for_irrep\fP (int irrep, const \fBRefSymmSCMatrix\fP &dhessian, const \fBRefSymmSCMatrix\fP &xhessian)"
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.RI "void \fBinit\fP ()"
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.RI "void \fBrestart\fP ()"
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.SS "Protected Attributes"

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.RI "\fBRef\fP< \fBMolecularEnergy\fP > \fBmole_\fP"
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.RI "\fBRef\fP< \fBPointGroup\fP > \fBdisplacement_point_group_\fP"
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.RI "\fBRef\fP< \fBPointGroup\fP > \fBoriginal_point_group_\fP"
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.RI "\fBRefSCVector\fP \fBoriginal_geometry_\fP"
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.RI "double \fBdisp_\fP"
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.RI "double \fBaccuracy_\fP"
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.RI "int \fBndisp_\fP"
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.RI "int \fBnirrep_\fP"
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.RI "int \fBrestart_\fP"
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.RI "char * \fBrestart_file_\fP"
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.RI "int \fBcheckpoint_\fP"
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.RI "char * \fBcheckpoint_file_\fP"
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.RI "int \fBonly_totally_symmetric_\fP"
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.RI "int \fBeliminate_cubic_terms_\fP"
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.RI "int \fBdo_null_displacement_\fP"
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.RI "int \fBdebug_\fP"
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.RI "\fBRefSCMatrix\fP \fBsymbasis_\fP"
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.RI "\fBRefSCVector\fP * \fBgradients_\fP"
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.SS "Additional Inherited Members"
.SH "Detailed Description"
.PP 
Computes the molecular hessian by finite displacements of gradients\&. 

This will use the minimum number of displacements, each in the highest possible point group\&. 
.SH "Constructor & Destructor Documentation"
.PP 
.SS "sc::FinDispMolecularHessian::FinDispMolecularHessian (const \fBRef\fP< \fBKeyVal\fP > &)"

.PP
The \fBFinDispMolecularHessian\fP \fBKeyVal\fP constructor is used to generate a \fBFinDispMolecularHessian\fP object from the input\&. It reads the keywords below\&.
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KeywordTypeDefaultDescription
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\fCenergy\fP\fBMolecularEnergy\fPnoneThis gives an object which will be used to compute the gradients needed to form the hessian\&. If this is not specified, the object using \fBFinDispMolecularHessian\fP 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\&.
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\fCdebug\fPbooleanfalseIf true, print out debugging information\&.
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\fCpoint_group\fP\fBPointGroup\fPnoneThe point group to use for generating the displacements\&.
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\fCrestart\fPbooleantrueIf true, and a checkpoint file exists, restart from that file\&.
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\fCrestart_file\fPstring \fIbasename\fP\fC\&.ckpt\&.hess\fPThe name of the file where checkpoint information is written to or read from\&.
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\fCcheckpoint\fPbooleantrueIf true, checkpoint intermediate data\&.
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\fConly_totally_symmetric\fPbooleanfalse 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\&.
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\fCeliminate_cubic_terms\fPbooleantrueIf 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\&.
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\fCdo_null_displacement\fPbooleantrueRun the calculation at the given geometry as well\&.
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\fCdisplacement\fPdouble1\&.0e-2The size of the displacement in Bohr\&.
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\fCgradient_accuracy\fPdouble\fCdisplacement\fP / 1000The accuracy to which the gradients will be computed\&.
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.SH "Member Function Documentation"
.PP 
.SS "\fBRefSymmSCMatrix\fP sc::FinDispMolecularHessian::cartesian_hessian ()\fC [virtual]\fP"

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This returns the cartesian hessian\&. If it has not yet been computed, it will be computed by finite displacements\&. 
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Implements \fBsc::MolecularHessian\fP\&.
.SS "\fBMolecularEnergy\fP* sc::FinDispMolecularHessian::energy () const\fC [virtual]\fP"

.PP
This returns a \fBMolecularEnergy\fP object, if used by this specialization\&. Otherwise null is returned\&. 
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Reimplemented from \fBsc::MolecularHessian\fP\&.
.SS "void sc::FinDispMolecularHessian::save_data_state (\fBStateOut\fP &)\fC [virtual]\fP"

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Save the base classes (with save_data_state) and the members in the same order that the \fBStateIn\fP CTOR initializes them\&. This must be implemented by the derived class if the class has data\&. 
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Reimplemented from \fBsc::SavableState\fP\&.
.SS "void sc::FinDispMolecularHessian::set_energy (const \fBRef\fP< \fBMolecularEnergy\fP > & energy)\fC [virtual]\fP"

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Some \fBMolecularHessian\fP specializations require a molecular energy object\&. The default implementations of this ignores the argument\&. 
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Reimplemented from \fBsc::MolecularHessian\fP\&.

.SH "Author"
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Generated automatically by Doxygen for MPQC from the source code\&.