MOLPRO

31 EXPLICITLY CORRELATED METHODS 236
31.7 Choosing the ansatz and the level of approximation
The Ansatz can be chosen using the ANSATZ option and/or by options on the command line.
3A Ansatz 3A;
3*A Ansatz 3A with EBC approximation
3B
Ansatz 3B
3*B Ansatz 3B with EBC approximation
3C
Ansatz 3C
3*C Ansatz 3C with EBC approximation
The ansatz can be further detailed by appending options in parenthesis, e.g.
ANSATZ=3B(D)
These options can be one of
D
FIX
FIXC
DX
Use diagonal ansatz
Use diagonal ansatz with fixed amplitudes (orbital invariant)
Use diagonal ansatz with fixed amplitudes and canonical orbitals
Use diagonal ansatz and assume X-matrix to be diagonal (only for
Ansatz 3A)
GBC Use GBC approximation (only for 3B, default in 3A)
EBC Use EBC approximation (same as *)
HX1
HY1
HY2
Use HX1 approximation (only for 3B).
Use HY1 approximation (only for 3B and 3C).
Use HY2 approximation (only for 3B and 3C).
HY Default hybrid approximation. HX1 and HY2 approximation in 3B,
HY2 in 3C.
NOZ
NOX
Neglect Z terms (only for 3B and 3C).
Neglect X terms (only for 3A and 3B).
Several options separated by commas can be given. For instance
ANSATZ=3C(FIX,HY1)
uses the diagonal ansatz 3C(D) with fixed coefficients and the hybrid (HY1) approximation.
Alternatively or in addition, the following options can be given on the command line:
DIAG=1
Use diagonal ansatz.
DIAGX=1
Use diagonal ansatz and assume X-matrix to be diagonal.
GBC=1
Use GBC approximation (only for 3B, default in 3A).
EBC=1 Use EBC approximation (same as *).
HYPRID=n
Use HYn approximation.
HYPRIDX=1 Use HX1 approximation.