MOLPRO

19 THE MCSCF PROGRAM MULTI 143
conv Threshold for orbital gradient (default 10 −2 ).)
econv Threshold for change of total energy (default 10 −6 ).
sconv Threshold for size of step (default 10 −3 ).
The default values can be modified using the global GTHRESH command (see section 6.11).
Normally, the above default values are appropriate.
19.8.3 Maximum number of iterations
MAXITER,maxit;
maxit is maximum number of iterations (default 20). If the calculation does not converge in
the default number of iterations, you should first think about the reason before increasing the
limit. In most cases the choice of active orbitals or of the optimized states is not appropriate (see
introduction of MULTI). The maximum allowed value of maxit is 40. If the calculation has not
converged in this number of iterations, it is likely that the active space is not reasonable. Note:
slow convergence can occur in RASSCF calculations if single excitations into weakly occupied
orbitals are present. These should be eliminated using
RESTRICT,-1,-1,orbital list
19.8.4 Test options
TEST,i1,i2,i3,...;
Activate testing options numbered i1, i2, ... . Please do not use unless you know what you are
doing!
19.8.5 Special optimization parameters
The following parameters can also be given as options on the MULTI command line.
STEP,radius,trust1,tfac1,trust2,tfac2;
Special parameters for augmented hessian method. For experts only!
GOPER,igop;
Use G-operator technique in microiterations (Default). If igop.lt.0 do not use G-operators.
COPT,ciacc,copvar,maxci,cishft,icimax,icimx1,icimx2,icstrt,icstep;
Special parameters for the direct CI method. For experts only!
ciacc
copvar
maxci
cishft
icimax
icimx1
icimx2
grad threshold for CI diagonalization
start threshold for CI-optimization
max. number of CI-optimizations per microiteration
denominator shift for q-space
max. number of CI-optimizations in first macroiteration
max. number of CI-optimizations in second and subsequent
iterations
max. number of CI-optimizations in internal absorption step