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

&CIFOPR – Specify different options in CI Property Module¶

PROPER¶

Activate the property module to evaluate expectation values of One-electron operators defined inside

PRPTRA under MOLTRA, over the DIRRCI wavefunction [Nayak2006], [Nayak2007], [Nayak2009].

Default:

PROPER=F

NEOPER¶

Define the number of property operators one needs to calculate expectation values.

Default:

NEOPER=0

NAMEE¶

Mention the names of One-electron operators as defined inside PRPTRA.

For example, Electric dipole moment and magnetic hyperfine structure constants

can be defined as follows. Of coures, the given names are users own choice.

NAMEE='Z-DIP','X1-HYP','Y1-HYP','Z1-HYP'