VWN  Dirac exchange with local VWN correlation [79,88].  
PZ81  Dirac exchange with local PZ81 correlation [79,89].  
PW92  Dirac exchange with local PW92 correlation [79,90].  
PW86  PW86 GGA exchange with P86 GGA correlation [80,91].  
BLYP  B88 GGA exchange with LYP GGA correlation [81,93,94,95].  
OLYP  HC01 GGA exchange with LYP GGA correlation [86,93,94,95].  
PW91  PW91 GGA exchange and correlation [82].  
PW91SSF  PW91 with full spin scaling function [82].  
PBE  PBE GGA exchange and correlation [83].  
PBESSF  PBE with full spin scaling function [83].  
PBESOL  PBE GGA exchange and correlation for solids [87,87].  
KT1/2/3  KT13 GGA exchange and correlation for NMR shieldings [100,101].  
SO11  SO11 GGA exchange and correlation [102].  
N12  N12 GGA exchange and correlation [103].  
GAM  GAM GGA exchange and correlation [104].  
CAP  CAP GGA exchange and correlation [105].  
VS98  VS98 metaGGA exchange and correlation [106].  
PKZB  PKZB metaGGA exchange and correlation [107].  
TPSS  TPSS metaGGA exchange and correlation [108,109].  
M06L  M06L metaGGA exchange and correlation [110].  
M11L  M11L metaGGA exchange and correlation [111].  
MN12  MN12 metaGGA exchange and correlation [112].  
B3LYP  B3LYP GGA hybrid exchange and correlation [62,63].  
BH&H  Becke halfandhalf GGA hybrid exchange and correlation [113].  
PBE0  PBE0 GGA hybrid exchange and correlation [64,65].  
M062X  M062X metaGGA hybrid exchange and correlation [66].  
M06HF  M06HF metaGGA hybrid exchange and correlation [66].  
M06  M06 metaGGA hybrid exchange and correlation [66].  
XALPHA  X calculation. The default value is 0.75. A user defined value can be selected with the X = Real option [114].  
FOCK  Variational fitted Fock exchange [115].  
NONE  No exchangecorrelation functional is used. 
AUXIS  The auxiliary function density is used for the calculation of the exchangecorrelation energy and matrix elements of the potential. This is the default.  
BASIS  The KohnSham density is used for the calculation of the exchangecorrelation energy and matrix elements of the potential. 
The syntax for userdefined combinations of functionals
is Exchange  Correlation (e.g. B88  P86). With the
option NONE, the exchange or correlation functional (or both) can be
omitted. Distinct from the literature, the PW86 exchange functional
is implemented in deMon2k with a cutoff and the local contribution of
the P86 correlation functional is calculated with the VWN functional.
The BH&H hybrid functional energy is defined in deMon2k as [113]:
(1) 

The AUXIS and BASIS options specify the density that is used for the calculation of the exchangecorrelation energy and matrix elements of the exchangecorrelation potential. By default, the auxiliary function density is used for both calculations, i.e. the auxiliary density functional theory approach is employed. The option BASIS invokes the KohnSham methodology. Note that this choice may slow down the calculation significantly. For metaGGAs the option BASIS must be specified. For Fock exchange the AUXIS and BASIS options are meaningless because it is always calculated by the variational fitting of the Fock potential. For more details and recommendations see Section 1.4, "How to Use deMon2k".
For the PW91 and PBE functionals, two different spin scaling functions are implemented in deMon2k. By default a numerically more stable cutoff function is used. By invoking the extension SSF (options PW91SSF and PBESSF), the originally published form of the spinscaling function is selected. This choice may change the orbital energies considerably, but for the total energies the effect is usually negligible.
