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sanya
sanya@photonics.ru

Yes, but it is not necessary. SCF calculation is not long. Moreover, you may re-use $TDVEC from the previous calculation if you really need. But if the functional in your previous calculation is not the same as in the current one, it is senseless.

>2) how large should be a parameter NSTATE when a molecule consisting of 40-60 atoms are calculated?

It depends on how many excited states you are interested in. If you are sure that your state of interest is 1st excited, set NSTATE=1, but it is better to set NSTATE as at least 3 or 4. It is not expensive. However, if you don't see any intense transitions while you are sure there should be some, you may increase NSTATE to 10 or even 20 (this takes really long time and requires more memory). This may happen with pure GGA functionals.

>3) to calculate triplet states the only parameter MULT should be changed or other additional options are necessary?

MULT=1 in $CONTRL and MULT=3 in $TDDFT. Otherwise, you'll get an error (the manual says that "the reference is necessarily single R-DFT"). You don't need to change other parameters.