Effective Core Potentials
Effective-core potentials (ECP) are invoked via the keyword
In addition, the use of ECPs requires that the keyword BASIS is set to SPECIAL and after that the basis-set keyword is need to be defined (as in GENBAS file) for each atom. Then (separated by a blank line), the keyword (as in ECPDATA file) to be used for ECPs need to be specified.
As an example, we show here an input for NiF6
NiF6 single-point energy calculation using an ECP for Ni NI F 1 R F 1 R 2 A F 1 R 3 A 2 T1 F 1 R 4 A 3 T2 F 1 R 5 A 4 T1 F 1 R 6 A 5 T2 R=1.676125 A=90. T1=90. T2=270. *CFOUR(CALC=HF,BASIS=SPECIAL,ECP=ON) NI:ECP-10-MDF F:DZP F:DZP F:DZP F:DZP F:DZP F:DZP NI:ECP-10-MDF F:NONE F:NONE F:NONE F:NONE F:NONE F:NONE
The calculation uses the .... ecp for Ni together with the corresponding basis set, while no ECP is specified for F (input NONE) and the corresponding basis set is DZP.
The ECPs must be provided in a similar manner as the basis-set via the ECPDATA file.
input and output example for a HF-SCF calculation with ECPs