### MOLSCAT User's Manual

# 6. NAMELIST block &CONV

If the variable ICONV in NAMELIST &INPUT is set to 1 on input, the program will
calculate S-matrices for successive values of the step size, RMIN, RMID or RMAX
and print out the root mean square (RMS) change in S-matrix elements and
transition probabilities each time. This provides an automated means of
choosing integration parameters capable of providing any required accuracy.
In this mode, the program performs NNRG calculations. Only a single energy
should be specified in the ENERGY array, and DNRG should be set to 0. Only a
single S-matrix is stored between calculations, so the program must not loop
over angular momenta or parity cases; thus JTOTU must be equal to JTOTL, and
MSET must be nonzero. Remember that, in some modes, MOLSCAT may determine RMIN,
RMID and RMAX internally, and it is safest to use the convergence testing with
these options switched off by setting the &INPUT variables IRMSET=0, RVFAC=0.,
IRXSET=0.

### IVAR

IVAR (default 0) selects which variable is to be altered.
Note that the first calculation is used as a
"reference" calculation (unless ICONVU .lt. 0, see
below), so that the subsequent calculations must be
less accurate than the first, not more accurate. For
successive calculations, IVAR is used as follows:
IVAR=0: step size is doubled each time. IVAR=1: RMIN
is increased by DR each time. IVAR=2: RMID is
increased by DR each time. IVAR=3: RMAX is decreased
by DR each time.

### DR

DR is the amount by which RMIN or RMID is increased or
RMAX is decreased in successive calculations.

### ICONVU

ICONV (default 0) is used if convergence information is to
be transferred from one run of MOLSCAT to another.
This is useful if the results obtained using two
different propagators are to be compared. If ICONVU
.gt. 0 on input, the first S-matrix is written out
(unformatted) to channel ICONVU; if ICONVU .lt. 0, a
previously saved S-matrix is read from channel |ICONVU|,
and used as the reference S-matrix in calculating RMS errors.

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