OBChargeModel Class Reference

Atomic partial charge models. More...

#include <openbabel/chargemodel.h>

Inheritance diagram for OBChargeModel:

List of all members.

Public Types

typedef std::map< const char
*, OBPlugin *, CharPtrLess

Public Member Functions

const char * TypeID ()
virtual bool ComputeCharges (OBMol &)
const std::vector< double > & GetFormalCharges () const
const std::vector< double > & GetPartialCharges () const
vector3 GetDipoleMoment (OBMol &)
virtual const char * Description ()
virtual bool Display (std::string &txt, const char *param, const char *ID=NULL)
virtual OBPluginMakeInstance (const std::vector< std::string > &)
virtual void Init ()
const char * GetID () const
virtual PluginMapTypeGetMap () const =0

Static Public Member Functions

static OBPluginGetPlugin (const char *Type, const char *ID)
static bool ListAsVector (const char *PluginID, const char *param, std::vector< std::string > &vlist)
static void List (const char *PluginID, const char *param=NULL, std::ostream *os=&std::cout)
static std::string ListAsString (const char *PluginID, const char *param=NULL)
static std::string FirstLine (const char *txt)
static PluginIterator Begin (const char *PluginID)
static PluginIterator End (const char *PluginID)

Protected Member Functions

void FillChargeVectors (OBMol &mol)
virtual double DipoleScalingFactor ()

Static Protected Member Functions

static PluginMapTypePluginMap ()
static PluginMapTypeGetTypeMap (const char *PluginID)
static OBPluginBaseFindType (PluginMapType &Map, const char *ID)

Protected Attributes

std::vector< double > m_partialCharges
std::vector< double > m_formalCharges
const char * _id

Detailed Description

Atomic partial charge models.

version 2.3

Classes derived from OBChargeModel implement different atomic partial charge models. It is intended to allow assinging partial charges beyond the traditional Gasteiger-Marsili sigma charges previously used in Open Babel. A --partialcharge method is provided for the babel command-line, allowing you to override the Gasteiger charge assignment and use other charge models.

The advantage of plugin classes is that no existing code has to be modified when a new class is added. You can list those that are present by babel -L charges or from a menu item in the GUI.

Any OBChargeModel derived class works like other plugins and needs to to have a constructor, a function returning a short description, and a ComputeCharges() function which does the work. A single global instance of the class needs to be instantiated to define the ID, by which the class is subsequently accessed.

Once ComputeCharges() has been called, the atoms of the molecule can be queried for partial or formal charges using OBAtom::GetPartialCharge() or in vector form from the model itself:

  OBMol inputMolecule;
  OBChargeModel *mmffCharges = OBChargeModel::FindType("mmff94");
  const std::vector<double> partialCharges;
  if (mmffCharges && mmffCharges->ComputeCharges(inputMolecule)) {
    partialCharges = mmffCharges->GetPartialCharges();

Note: Formal charges are also returned as floating point values, since some charge models consider delocalized charges (e.g., 0.5 for an O in a carboxylate CO2- group).

  OBChargeModel *gasteiger = OBChargeModel::FindType("gasteiger");
  if (gasteiger) {
    cout << " gasteiger: " << dipoleMagnitude(gasteiger->GetDipoleMoment(mol));

By default, Open Babel 2.3 includes Gasteiger and MMFF94 partial charges. If the Eigen matrix library is found when compiling, the QEq and QTPIE methods will be added. Future releases will likely add additional charge models, including the EEM method.

Member Typedef Documentation

typedef std::map<const char*, OBPlugin*, CharPtrLess> PluginMapType [inherited]

Member Function Documentation

const char* TypeID (  ) [inline, virtual]

Redefined by each plugin type: "formats", "fingerprints", etc.

Reimplemented from OBPlugin.

virtual bool ComputeCharges ( OBMol  ) [inline, virtual]
whether partial charges were successfully assigned to this molecule
The method should fill m_partialCharges and m_formalCharges as well
const std::vector<double>& GetFormalCharges (  ) const [inline]
a vector of the formal charges on each atom, indexed from 0 This method returns floating point formal charges since some charge models consider fractional charges (e.g., 0.5 for an oxygen in a carboxylate CO2- group).
If ComputeCharges() has not been called, this will return an empty vector
const std::vector<double>& GetPartialCharges (  ) const [inline]
a vector of the partial charges on each atom, indexed from 0
If ComputeCharges() has not been called, this will return an empty vector
vector3 GetDipoleMoment ( OBMol mol )
a vector of the dipole moment from this molecule
void FillChargeVectors ( OBMol mol ) [protected]

Fill the internal partial and formal charge vectors (convenience function)

virtual double DipoleScalingFactor (  ) [inline, protected, virtual]

Provide a scaling factor for the dipole moment -- ideally calibrated from many molecules.

Member Data Documentation

std::vector<double> m_partialCharges [protected]
std::vector<double> m_formalCharges [protected]

The documentation for this class was generated from the following files:
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