DIRRCI – Direct CI module¶

Relativistic RASCI module written by Lucas Visscher

This section allows for Kramers unrestricted relativistic Configuration Interaction calculations, Ref. [MOLFDIR].

Note that when the namelist GOSCIP – COSCI module is also present in the input, GOSCIP will be called instead of DIRRCI !

The input should be given in namelist form.

&CIROOT – Select the state to converge on¶

IREPNA¶

Abelian symmetry group of the desired state(s).

Default: First abelian symmetry in the list

NROOTS¶

Number of states to optimize on.

Default:

NROOTS=1

Advanced options

ISTART¶

Start vector method.

COSCI start vectors:

ISTART=1

Determinant with lowest eigenvalue:

ISTART=2

First (reference) determinant:

ISTART=3

If the COSCI start vectors are not available, then the default will be 2.

NSEL(NROOTS)¶

Rank number of states to be optimized.

Default:

NSEL=1,2,3,...

SELECT¶

Select wave functions on basis of largest overlap with the start wave function.

Default:

SELECT=F

&DIRECT – Convergence control¶

CONVERE¶

Convergence threshold for energy.

Default:

CONVERR=1.0D-9

MAXITER¶

Maximum number of direct CI iterations.

Default:

MAXITER=10

Advanced options

CONVERR¶

Convergence threshold for residual vector.

Default:

CONVERR=1.0D-10

RESTART¶

Restart on CI-vectors present in MRCFINV.

Default:

RESTART=F

CPUMAX¶

Maximum amount of CPU-seconds to be used.

Default:

CPUMAX=604800

&LEADDET – Analyze the CI wave function¶

Advanced options

GETDET¶

Get the list of dominant determinants.

Default:

GETDET=T

COMIN¶

Print contributions of determinants only if the square of the coefficients is larger than COMIN.

Default:

COMIN=0.1

&OPTIM – Fine tuning of the algorithm¶

Programmers options

IGENEX¶

Write coupling coefficients to file (default):

IGENEX=2

Calculate coupling coefficients when needed:

IGENEX=1

&RASORB – Specify the type of CI and the active space¶

NELEC¶

Number of electrons (excluding frozen core electrons).

Default:

NELEC=0

NRAS1¶

Number of spinors in the RAS1 space for each abelian irrep.

Default:

NRAS1=NSYMRP*0

NRAS2¶

Number of spinors in the RAS2 space for each abelian irrep.

Default:

NRAS2=NSYMRP*0

MAXH1¶

Maximum number of holes in RAS1 spinors.

Default:

MAXH1=0

MAXE3¶

Maximum number of electrons in RAS3 spinors.

Default:

MAXE3=0