$GUGDIA

$GUGDIA group (optional, relevant for -CI- or -MCSCF-)

This group provides control over the Davidson method diagonalization step.

NSTATE

= Number of CI states to be found. (default=1) You can solve for any number of states, but only 100 can be saved for subsequent sections, such as state averaging.

PRTTOL

= Printout tolerance for CI coefficients (default = 0.05)

MXXPAN

= Maximum no. of expansion basis vectors used before the expansion basis is truncated. (default=30)

ITERMX

= Maximum number of iterations (default=50)

CVGTOL

= Convergence criterion for Davidson eigenvector routine. This value is proportional to the accuracy of the coeficients of the eigenvector(s) found. The energy accuracy is proportional to its square. (default = 1.0E-5)

NWORD

= Number of words of fast memory to use in this step. A value of zero results in the use of all available memory. (default = 0)

MEMMAX

= 1000*limgiv + limh where limgiv is the largest matrix diagonalized via Givens-Householder (default=50) and limh is the dimension of the largest Hamiltonian that may be memory resident (default=100)

NIMPRV

= Maximum no. of eigenvectors to be improved every iteration. (default = nstate)

NSELCT

= Determines initial guess to eigenvectors.

= 0 -> Unit vectors corresponding to the NSTATE lowest diagonal elements and any diagonal elements within SELTHR of them. (default)

< 0 -> First abs(NSELCT) unit vectors.

> 0 -> use NSELCT unit vectors corresponding to the NSELCT lowest diagonal elements.

SELTHR

= Guess selection threshold when NSELCT=0. (default=0.01)

NEXTRA

= Number of extra expansion basis vectors to be included on the first iteration. NEXTRA is decremented by one each iteration. This may be useful in "capturing" vectors for higher states. (default=0)

KPRINT

= Print flag bit vector used when NPFLG(4)=1 in the $CIINP group (default=8)
value 1 bit 0 print final eigenvalues
value 2 bit 1 print final tolerances
value 4 bit 2 print eigenvalues and tolerances at each truncation
value 8 bit 3 print eigenvalues every iteration
value 16 bit 4 print tolerances every iteration