ATOM

Purpose

A quantum mechanical atom with a basis set

Synopsis

This object is used both for positional information and basis set information. Atomic natural orbitals and occupations are stored for Roby population analysis reasons.

Information about thermal motion (for X-ray calcculations) is also stored, as well as Bragg-Slater radii and nuetron scattering lengths.

Default input data order

ATOM_INPUT_DATA_ORDER     [ label= pos= basis_label= ]

Listing of keywords

axis_system= STR

Read a string which describes the axis system.

  • Currently allowed options are cartesian or crystal

  • Note that the thermal_axis_system is changed to be the same as the axis_system

basis= BASIS

Read a complete basis set.

basis_label= STR

Read only a the basis set label for the atom.

  • Modules which use the ATOM module may resolve the missing basis set information from a library file, or from an inputted BASISVEC object.

group= INT

Read an integer index which represents the group the atom belongs to.

  • Different atoms which have the same index belong in the same group.

  • The index can be used, for example, when calculating the properties of a group of atoms within a molecule, or interaction between groups of atoms.

junk= STR

Read in a junk string

  • This is useful for ignoring a data field from input which has not been generated by TONTO

label= INT|STR

Read in an atom label.

  • If the atom label is an integer it is assumed to be the atomic number of the atom

  • If the atom label is a string, the first two characters must be the periodic table symbol for that atom followed by (optionally) an integer, for example Cu13

pos= REALVEC(3)

Read in the position of the atom in some axis_system

  • Refer to the axis_system keyword

  • If the axis_system is crystal, the positions in cartesian coordinates can only be determined when information about a corresponding CRYSTAL is provided

  • Refer to the resolve_axis_system routine

put

Print out information about the atom to stdout in human readable form.

thermal_axis_system= STR

Read a string which describes the axis system for the thermal_tensor of the atom.

  • Currently allowed options are cartesian or crystal

  • This keyword is only required for cases where the axis_system and thermal_axis_system are different

  • Refer to the thermal_tensor= keyword.

thermal_tensor= REALVEC(6)

Read in the anisotropic Debye-Waller factors or thermal tensor U for the atom in the order U11 U22 U33 U12 U13 U23

  • For a definition of the thermal tensor see the read_thermal_tensor routine

  • Be careful with units; the U tensor is often given in angstrom^2 units

units= STR

Read a string which describes the units of the next inputted numerical entity; that is, the next real or complex number, real or complex vector, or real or complex matrix.

  • The default atomic units are restored after the numerical entity has been inputted

  • Warning: if the next inputted datum is not a numerical entity, the new units keyword remains in force