Firefly and PC GAMESS-related discussion club

Learn how to ask questions correctly

Alex Granovsky
gran@classic.chem.msu.su

It seems I do need to make some comments concerning your questions.

>1- What is the function of the $DRT group in the above input file? As far as I understand, the CISTEP=ALDET keyword should make the program use the Ames Lab determinant CI and read the settings in the $DET group. Doesn’t this make the $DRT group (as well as the associated $GUGEM, $GUGDM2, and $GUGDIA groups) nonfunctional?

That's true. However, this particular input file was designed
mainly to test various hardware. Sometimes, we also check the
performance of GUGA code vs. ALDET; so it is very helpful to have
the bimodal input that can be used with GUGA as well as with ALDET.


>2- What is the function of the NSTATE keyword in the $MCQDPT group and what is its relation to the KSTATE keyword? At first glance, it seems that NSTATE is for the inclusion of more than one state in the MCQDPT part of the calculation, but I thought that this is what KSTATE is for. Incidentally, I have performed a few MCQDPT2 calculations with either keyword (NSTATE=2 or KSTATE(1)=1,1), but the differences in energy where negligible.

Firefly accept both kstate(1) and nstate input in $mcqdpt and $xmcqdpt
groups. Assume you set nstate to 5. Internally, this just sets kstate
array to kstate(1)=1,1,1,1,1,0,... The nstate input is typically
more convenient, while kstate input is more flexible so you can
use the one that is more suitable for your purposes.

>3- And finally, what does the IROT keyword in the $MCQDPT group do? Its function unfortunately is not described in the most up-to-date Firefly documentation as well as the current GAMESS US documentation.

Setting irot to 1, you select modified XMCQDPT2 and MCQDPT2
calculations that apply MP2-like expression for double  
excitations from double occupied inactive orbitals to
external MOs. Normally, this improves results of MCQDPT2
(but does not improve XMCQDPT2), and also saves lots of
computational time (once again, the latter is not the
case for table-driven approach).

Regards,
Alex Granovsky





On Mon Oct 18 '10 3:03pm, Thomas wrote
--------------------------------------
>Dear fellow Firefly users,

>I’m quite new to Firefly and am currently learning how to properly do CASSCF and MCQDPT calculations. I’ve studied a number of example input files in order to learn which keywords are important for these types of calculations, but this has raised a few questions which I, so far, have been unable to find an answer to. Specifically, I have a hard time understanding what some of the groups/keywords in the MCQDPT2/retinal benchmark are for. This is what the input file of this benchmark looks like.
>
>
>$contrl icharg=1 scftyp=mcscf d5=.t. icut=10 inttyp=hondo mplevl=2
> exetyp=timing $end
> $system mwords=200 timlim=100000 mklnp=4 $end
> $smp csmtx=.t. $end
> $guess guess=moread norb=540 kdiag=0 $end
> $trans dirtrf=.t. mptran=2 mode=112 $end                                      
> $mcscf maxit=100 cistep=aldet $end
> $drt group=c1 fors=.t. nmcc=88 ndoc=6 nval=6 $end
> $det group=c1 ncore=88 nact=12 nels=12 nstate=3 wstate(1)=1,1 $end
> $gugem pack2=1 $end
> $gugdm2 wstate(1)=1.,1. $end
> $gugdia nstate=2 $end
> $mcqdpt nstate=2 edshft=0.02 irot=1 thrgen=1d-12 $end
>
>
>My questions are the following:

>1- What is the function of the $DRT group in the above input file? As far as I understand, the CISTEP=ALDET keyword should make the program use the Ames Lab determinant CI and read the settings in the $DET group. Doesn’t this make the $DRT group (as well as the associated $GUGEM, $GUGDM2, and $GUGDIA groups) nonfunctional?

>2- What is the function of the NSTATE keyword in the $MCQDPT group and what is its relation to the KSTATE keyword? At first glance, it seems that NSTATE is for the inclusion of more than one state in the MCQDPT part of the calculation, but I thought that this is what KSTATE is for. Incidentally, I have performed a few MCQDPT2 calculations with either keyword (NSTATE=2 or KSTATE(1)=1,1), but the differences in energy where negligible.

>3- And finally, what does the IROT keyword in the $MCQDPT group do? Its function unfortunately is not described in the most up-to-date Firefly documentation as well as the current GAMESS US documentation.
>
>
>I would be very thankful if someone could shine some light on these topics. Many thanks in advance.
>
>
>Kind regards,
>Thom
>