`SPLITTING`- runs the tunnelling splitting calculation instead of a rate calculation. The default is False.
`INPUT`=*filename*- file containing initial instanton geometry in format described in section 50.3. The default is initial.xyz.
`OUTPUT`=*filename*- file containing final instanton geometry in format described in section 50.3. The default is final.xyz.
`REACTANT`=*value*- value of potential (in ) of reactant states used to scale the instanton action in a rate calculation only. The default is 0.
`MAXIT`=*integer*- maximum number of optimization cycles. The default is 50.
`GRADIENT`=*value*- required accuracy of the optimized ring-polymer gradient. The default is .
`STEPMAX`=*value*- maximum allowed step (in bohr) in the quasi-Newton instanton optimization. Attempted steps larger than this are scaled down. The default is .
`MSAVE`=*integer*- number of gradients saved from previous iterations used in the L-BFGS optimization. The default is 3.
`READ`- Reads initial (pre-optimized) Hessian from file
`$TMPDIR/instanton.hess`, which is automatically created from the final geometry of the previous run, instead of calling`beadfreq2`. The default is False. `READ`- Uses a banded-matrix eigensolver in the quasi-Newton optimization. The default is False.

molpro@molpro.net 2019-05-24