Package org.openscience.cdk

Class Atom

java.lang.Object
org.openscience.cdk.ChemObject
org.openscience.cdk.Element
org.openscience.cdk.Isotope
org.openscience.cdk.AtomType
org.openscience.cdk.Atom
All Implemented Interfaces:
Serializable, Cloneable, IAtom, IAtomType, ICDKObject, IChemObject, IElement, IIsotope
Direct Known Subclasses:
DebugAtom, PDBAtom, PharmacophoreAtom, PharmacophoreQueryAtom, PseudoAtom
public class Atom extends AtomType implements IAtom, Serializable, Cloneable
Represents the idea of an chemical atom.

An Atom class is instantiated with at least the atom symbol: 

   Atom a = new Atom("C");

Once instantiated all field not filled by passing parameters to the constructor are null. Atoms can be configured by using the IsotopeFactory.configure() method: 

   IsotopeFactory if = IsotopeFactory.getInstance(a.getNewBuilder());
   if.configure(a);

More examples about using this class can be found in the Junit test for this class.

Author:
steinbeck
See Also:
Keywords:
atom
Created on:
2000-10-02

  • Field Details

    • point2d

      protected javax.vecmath.Point2d point2d
      A 2D point specifying the location of this atom in a 2D coordinate space.

    • point3d

      protected javax.vecmath.Point3d point3d
      A 3 point specifying the location of this atom in a 3D coordinate space.

    • fractionalPoint3d

      protected javax.vecmath.Point3d fractionalPoint3d
      A 3 point specifying the location of this atom in a crystal unit cell.

    • hydrogenCount

      protected Integer hydrogenCount
      The number of implicitly bound hydrogen atoms for this atom.

    • stereoParity

      protected Integer stereoParity
      A stereo parity descriptor for the stereochemistry of this atom.

    • charge

      protected Double charge
      The partial charge of the atom. The default value is CDKConstants.UNSET and serves to provide a check whether the charge has been set or not

  • Constructor Details

    • Atom

      public Atom()
      Constructs an completely unset Atom.

    • Atom

      public Atom(int elem)
      Create a new atom with of the specified element.
      Parameters:
      elem - atomic number

    • Atom

      public Atom(int elem, int hcnt)
      Create a new atom with of the specified element and hydrogen count.
      Parameters:
      elem - atomic number
      hcnt - hydrogen count

    • Atom

      public Atom(int elem, int hcnt, int fchg)
      Create a new atom with of the specified element, hydrogen count, and formal charge.
      Parameters:
      elem - atomic number
      hcnt - hydrogen count
      fchg - formal charge

    • Atom

      public Atom(String symbol)
      Constructs an Atom from a string containing an element symbol and optionally the atomic mass, hydrogen count, and formal charge. The symbol grammar allows easy construction from common symbols, for example: 
           new Atom("NH+");   // nitrogen cation with one hydrogen
     new Atom("OH");    // hydroxy
     new Atom("O-");    // oxygen anion
     new Atom("13CH3"); // methyl isotope 13
 
           atom := {mass}? {symbol} {hcnt}? {fchg}?
     mass := \d+
     hcnt := 'H' \d+
     fchg := '+' \d+? | '-' \d+?
      Parameters:
      symbol - string with the element symbol

    • Atom

      public Atom(String elementSymbol, javax.vecmath.Point3d point3d)
      Constructs an Atom from an Element and a Point3d.
      Parameters:
      elementSymbol - The symbol of the atom
      point3d - The 3D coordinates of the atom

    • Atom

      public Atom(String elementSymbol, javax.vecmath.Point2d point2d)
      Constructs an Atom from an Element and a Point2d.
      Parameters:
      elementSymbol - The Element
      point2d - The Point

    • Atom

      public Atom(IElement element)
      Constructs an isotope by copying the symbol, atomic number, flags, identifier, exact mass, natural abundance, mass number, maximum bond order, bond order sum, van der Waals and covalent radii, formal charge, hybridization, electron valency, formal neighbour count and atom type name from the given IAtomType. It does not copy the listeners and properties. If the element is an instance of IAtom, then the 2D, 3D and fractional coordinates, partial atomic charge, hydrogen count and stereo parity are copied too.
      Parameters:
      element - IAtomType to copy information from

    • Atom

      public Atom(IAtom org)
      Constructs an isotope by copying the symbol, atomic number, flags, identifier, exact mass, natural abundance, mass number, maximum bond order, bond order sum, van der Waals and covalent radii, formal charge, hybridization, electron valency, formal neighbour count and atom type name from the given IAtomType. It does not copy the listeners and properties. If the element is an instance of IAtom, then the 2D, 3D and fractional coordinates, partial atomic charge, hydrogen count and stereo parity are copied too.
      Parameters:
      org - IAtomType to copy information from

  • Method Details

    • getContainer

      public IAtomContainer getContainer()
      Access the IAtomContainer of which this atom is a member of. Because atoms can be in multiple molecules this method will only work if the atom has been accessed in the context of an IAtomContainer, for example: 
      
 IAtomContainer mol  = new AtomContainer();
 IAtom          atom = new Atom(6);

 atom.getContainer(); // null
 mol.add(atom);
 atom.getContainer(); // still null
 mol.getAtom(0).getContainer(); // not-null, returns 'mol'
      Specified by:
      getContainer in interface IAtom
      Returns:
      the atom container or null if not accessed in the context of a container

    • getIndex

      public int getIndex()
      Acces the index of an atom in the context of an IAtomContainer. If the index is not known, < 0 is returned.
      Specified by:
      getIndex in interface IAtom
      Returns:
      atom index or < 0 if the index is not known

    • bonds

      public Iterable<IBond> bonds()
      Returns the bonds connected to this atom. If the bonds are not known an exception is thrown. This method will only throw an exception if IAtom.getIndex() returns < 0 or IAtom.getContainer() returns null. 
      

 IAtom atom = ...;

 if (atom.getIndex() >= 0) {
   for (IBond bond : atom.bonds()) {

   }
 }

 if (atom.getContainer() != null) {
   for (IBond bond : atom.bonds()) {

   }
 }

 IAtomContainer mol = ...;
 // guaranteed not throw an exception
 for (IBond bond : mol.getAtom(i).bonds()) {

 }
      Specified by:
      bonds in interface IAtom
      Returns:
      iterable of bonds

    • getBondCount

      public int getBondCount()
      Get the number of explicit bonds connected to this atom.
      Specified by:
      getBondCount in interface IAtom
      Returns:
      the total bond count

    • getBond

      public IBond getBond(IAtom atom)
      Returns the bond connecting 'this' atom to the provided atom. If the atoms are not bonded, null is returned.
      Specified by:
      getBond in interface IAtom
      Parameters:
      atom - the other atom
      Returns:
      the bond connecting the atoms

    • setCharge

      public void setCharge(Double charge)
      Sets the partial charge of this atom.
      Specified by:
      setCharge in interface IAtom
      Parameters:
      charge - The partial charge
      See Also:

    • getCharge

      public Double getCharge()
      Returns the partial charge of this atom. If the charge has not been set the return value is Double.NaN
      Specified by:
      getCharge in interface IAtom
      Returns:
      the charge of this atom
      See Also:

    • setImplicitHydrogenCount

      public void setImplicitHydrogenCount(Integer hydrogenCount)
      Sets the number of implicit hydrogen count of this atom.
      Specified by:
      setImplicitHydrogenCount in interface IAtom
      Parameters:
      hydrogenCount - The number of hydrogen atoms bonded to this atom.
      See Also:

    • getImplicitHydrogenCount

      public Integer getImplicitHydrogenCount()
      Returns the hydrogen count of this atom.
      Specified by:
      getImplicitHydrogenCount in interface IAtom
      Returns:
      The hydrogen count of this atom.
      See Also:

    • setPoint2d

      public void setPoint2d(javax.vecmath.Point2d point2d)
      Sets a point specifying the location of this atom in a 2D space.
      Specified by:
      setPoint2d in interface IAtom
      Parameters:
      point2d - A point in a 2D plane
      See Also:

    • setPoint3d

      public void setPoint3d(javax.vecmath.Point3d point3d)
      Sets a point specifying the location of this atom in 3D space.
      Specified by:
      setPoint3d in interface IAtom
      Parameters:
      point3d - A point in a 3-dimensional space
      See Also:

    • setFractionalPoint3d

      public void setFractionalPoint3d(javax.vecmath.Point3d point3d)
      Sets a point specifying the location of this atom in a Crystal unit cell.
      Specified by:
      setFractionalPoint3d in interface IAtom
      Parameters:
      point3d - A point in a 3d fractional unit cell space
      See Also:

    • setStereoParity

      public void setStereoParity(Integer stereoParity)
      Sets the stereo parity for this atom.
      Specified by:
      setStereoParity in interface IAtom
      Parameters:
      stereoParity - The stereo parity for this atom
      See Also:

    • getPoint2d

      public javax.vecmath.Point2d getPoint2d()
      Returns a point specifying the location of this atom in a 2D space.
      Specified by:
      getPoint2d in interface IAtom
      Returns:
      A point in a 2D plane. Null if unset.
      See Also:

    • getPoint3d

      public javax.vecmath.Point3d getPoint3d()
      Returns a point specifying the location of this atom in a 3D space.
      Specified by:
      getPoint3d in interface IAtom
      Returns:
      A point in 3-dimensional space. Null if unset.
      See Also:

    • getFractionalPoint3d

      public javax.vecmath.Point3d getFractionalPoint3d()
      Returns a point specifying the location of this atom in a Crystal unit cell.
      Specified by:
      getFractionalPoint3d in interface IAtom
      Returns:
      A point in 3d fractional unit cell space. Null if unset.
      See Also:

    • getStereoParity

      public Integer getStereoParity()
      Returns the stereo parity of this atom. It uses the predefined values found in CDKConstants.
      Specified by:
      getStereoParity in interface IAtom
      Returns:
      The stereo parity for this atom
      See Also:

    • compare

      public boolean compare(Object object)
      Compares a atom with this atom.
      Overrides:
      compare in class AtomType
      Parameters:
      object - of type Atom
      Returns:
      true, if the atoms are equal

    • getMapIdx

      public int getMapIdx()
      Description copied from interface: IAtom
      Access the map index for this atom.
      Specified by:
      getMapIdx in interface IAtom
      Returns:
      the map index (0 if not set)

    • setMapIdx

      public void setMapIdx(int mapidx)
      Description copied from interface: IAtom
      Set the map index for this atom.
      Specified by:
      setMapIdx in interface IAtom
      Parameters:
      mapidx - the new map index

    • toString

      public String toString()
      Returns a one line string representation of this Atom. Methods is conform RFC #9.
      Specified by:
      toString in interface IChemObject
      Overrides:
      toString in class AtomType
      Returns:
      The string representation of this Atom

    • clone

      public IAtom clone() throws CloneNotSupportedException
      Clones this atom object and its content.
      Specified by:
      clone in interface IAtom
      Specified by:
      clone in interface IChemObject
      Overrides:
      clone in class AtomType
      Returns:
      The cloned object
      Throws:
      CloneNotSupportedException - if the IChemObject cannot be cloned

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object