20.1 Structure of the input

All sub-commands known to MULTI may be abbreviated by four letters. The input commands fall into several logical groups; within each group commands may appear in any order, but the groups must come in correct order.

a)

The program is invoked by the command MULTI or MCSCF

b)

cards defining partitioning of orbitals spaces - OCC,FROZEN,CLOSED

c)

general options (most commands not otherwise specified here)

d)

a WF card defining a state symmetry

e)

options pertaining to that state symmetry - WEIGHT,STATE,LQUANT

f)

configuration specification for that state symmetry - SELECT,CON,RESTRICT

g)

definition of the primary configurations for that state symmetry - PSPACE

h)

further general options

Stages d) through to h) may be repeated several times; this is the way in which you specify an average energy of several states of different symmetry.

Many options can be specified on the MULTI command line:

MULTI,options

Selected options:

MAXIT

Max. number of iterations (default 10)

ENERGY

Convergence threshold for energy

GRADIENT

Convergence threshold for gradient

STEP

Convergence threshold for steplength

FAILSAFE

(logical) Use options for more robust convergence

Many further options and thresholds, which can also be given on the command line, are described in section 20.8.5.