# pymatgen.core.xcfunc module

This module provides

class XcFunc(xc=None, x=None, c=None)

  Bases: `monty.json.MSONable`

  This object stores information about the XC correlation functional. Client code usually creates the object by calling the class methods:

  > - from_name

  > - from_type_name

  or code-specific methods such as:

  > - from_abinit_ixc

  Ax XcFunc instance is hashable and can therefore be used as key in dictionaries.

  The implementation is based on the libxc conventions and is inspired to the XML specification for atomic PAW datasets documented at:

  > https://wiki.fysik.dtu.dk/gpaw/setups/pawxml.html

  For convenience, part of the pawxml documentation is reported here.

  The xc_functional element defines the exchange-correlation functional used for generating the dataset. It has the two attributes type and name.

  The type attribute can be LDA, GGA, MGGA or HYB. The name attribute designates the exchange-correlation functional and can be specified in the following ways:

  [1] Taking the names from the LibXC library. The correlation and exchange names

    are stripped from their XC_ part and combined with a + sign. Here is an example for an LDA functional:

    <xc_functional type=”LDA”, name=”LDA_X+LDA_C_PW”/>

    and this is what PBE will look like:

    <xc_functional type=”GGA”, name=”GGA_X_PBE+GGA_C_PBE”/>

  [2] Using one of the following pre-defined aliases:

  type name LibXC equivalent Reference LDA PW LDA_X+LDA_C_PW LDA exchange; Perdew, Wang, PRB 45, 13244 (1992) GGA PW91 GGA_X_PW91+GGA_C_PW91 Perdew et al PRB 46, 6671 (1992) GGA PBE GGA_X_PBE+GGA_C_PBE Perdew, Burke, Ernzerhof, PRL 77, 3865 (1996) GGA RPBE GGA_X_RPBE+GGA_C_PBE Hammer, Hansen, Nørskov, PRB 59, 7413 (1999) GGA revPBE GGA_X_PBE_R+GGA_C_PBE Zhang, Yang, PRL 80, 890 (1998) GGA PBEsol GGA_X_PBE_SOL+GGA_C_PBE_SOL Perdew et al, PRL 100, 136406 (2008) GGA AM05 GGA_X_AM05+GGA_C_AM05 Armiento, Mattsson, PRB 72, 085108 (2005) GGA BLYP GGA_X_B88+GGA_C_LYP Becke, PRA 38, 3098 (1988); Lee, Yang, Parr, PRB 37, 785

  Parameters

    - xc – LibxcFunc for XC functional.

    - x – LibxcFunc for exchange and correlation part. Mutually exclusive with xc.

    - c – LibxcFunc for exchange and correlation part. Mutually exclusive with xc.

  abinitixc_to_libxc = {1: {'xc': LibxcFunc.LDA_XC_TETER93}, 2: {'c': LibxcFunc.LDA_C_PZ, 'x': LibxcFunc.LDA_X}, 4: {'c': LibxcFunc.LDA_C_WIGNER, 'x': LibxcFunc.LDA_X}, 5: {'c': LibxcFunc.LDA_C_HL, 'x': LibxcFunc.LDA_X}, 7: {'c': LibxcFunc.LDA_C_PW, 'x': LibxcFunc.LDA_X}, 11: {'c': LibxcFunc.GGA_C_PBE, 'x': LibxcFunc.GGA_X_PBE}, 14: {'c': LibxcFunc.GGA_C_PBE, 'x': LibxcFunc.GGA_X_PBE_R}, 15: {'c': LibxcFunc.GGA_C_PBE, 'x': LibxcFunc.GGA_X_RPBE}}
  classmethod aliases()

    List of registered names.

  as_dict()

    Makes XcFunc obey the general json interface used in pymatgen for easier serialization.

  classmethod asxc(obj)

    Convert object into Xcfunc.

  defined_aliases = OrderedDict([((<LibxcFunc.LDA_X: 1>, <LibxcFunc.LDA_C_PW: 12>), type_name(type='LDA', name='PW')), ((<LibxcFunc.LDA_X: 1>, <LibxcFunc.LDA_C_PW_MOD: 13>), type_name(type='LDA', name='PW_MOD')), ((<LibxcFunc.LDA_X: 1>, <LibxcFunc.LDA_C_PZ: 9>), type_name(type='LDA', name='PZ')), ((<LibxcFunc.LDA_X: 1>, <LibxcFunc.LDA_C_WIGNER: 2>), type_name(type='LDA', name='W')), ((<LibxcFunc.LDA_X: 1>, <LibxcFunc.LDA_C_HL: 4>), type_name(type='LDA', name='HL')), ((<LibxcFunc.LDA_X: 1>, <LibxcFunc.LDA_C_GL: 5>), type_name(type='LDA', name='GL')), ((<LibxcFunc.LDA_X: 1>, <LibxcFunc.LDA_C_VWN: 7>), type_name(type='LDA', name='VWN')), ((<LibxcFunc.GGA_X_PW91: 109>, <LibxcFunc.GGA_C_PW91: 134>), type_name(type='GGA', name='PW91')), ((<LibxcFunc.GGA_X_PBE: 101>, <LibxcFunc.GGA_C_PBE: 130>), type_name(type='GGA', name='PBE')), ((<LibxcFunc.GGA_X_RPBE: 117>, <LibxcFunc.GGA_C_PBE: 130>), type_name(type='GGA', name='RPBE')), ((<LibxcFunc.GGA_X_PBE_R: 102>, <LibxcFunc.GGA_C_PBE: 130>), type_name(type='GGA', name='revPBE')), ((<LibxcFunc.GGA_X_PBE_SOL: 116>, <LibxcFunc.GGA_C_PBE_SOL: 133>), type_name(type='GGA', name='PBEsol')), ((<LibxcFunc.GGA_X_AM05: 120>, <LibxcFunc.GGA_C_AM05: 135>), type_name(type='GGA', name='AM05')), ((<LibxcFunc.GGA_X_B88: 106>, <LibxcFunc.GGA_C_LYP: 131>), type_name(type='GGA', name='BLYP'))])
  classmethod from_abinit_ixc(ixc)

    Build the object from Abinit ixc (integer)

  classmethod from_dict(d)

    Makes XcFunc obey the general json interface used in pymatgen for easier serialization.

  classmethod from_name(name)

    Build the object from one of the registered names

  classmethod from_type_name(typ, name)

    Build the object from (type, name).

  name()

    The name of the functional. If the functional is not found in the aliases, the string has the form X_NAME+C_NAME

  type()

    The type of the functional.