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<DIV><FONT face=Arial size=2>Dear molpro users.</FONT></DIV>
<DIV><FONT face=Arial size=2>I am new to multi-reference calculations so I hoped
I could get some help on a problem.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I am trying to calculate the 3 long range PES is Cs
symmetry (1A' ,2A', 1A") for the Gallium (2P) + HCN interaction neglecting
spin-orbit. The ground electronic state of Ga-HCN (van der waals complex)
should be doublet sigma, where as HCN-Ga should be doublet pi. I have
confirmed this with single reference calculations. So I would like to do a
CASSCF(1,3) calculation with all three states weighted equally. I would
like to take this to higher levels (MRCI, or MRACPF etc..) but my question
starts with the CASSCF.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Here is my input:</FONT></DIV>
<DIV><FONT face=Arial size=2> gprint,civectors<BR>
mH=1.00794<BR> mC=12.0<BR> mN = 14.01<BR> rCH = 1.06<BR>
rCN = 1.17<BR> R = 3.5<BR> theta = 0.0<BR> rCM =
((mN*rCN)-(mH*rCH))/(mH+mC+mN)<BR> <BR> geometry=
{Z,ANGSTROM,<BR> C,<BR> X, C,
1.0,<BR> N, C, rCN, X, 90,<BR> H, C, rCH, X,
90, N, 180,<BR> X2, C, rCM, X, 90, N, 0,<BR>
Ga, X2, R, N, theta, X, 0,<BR> }<BR> basis =cc-pVDZ<BR>
i=0;<BR> Do theta=0.0,180.0,180.0,<BR> Do R=6.5,6.5,-0.2,<BR>
i=i+1<BR> T(i)=theta<BR> Rs(i)=R<BR> rhf<BR>
wf,45,2,1;<BR> multi,<BR> occ,19,6<BR> closed,17,5<BR>
wf,45,1,1;STATE,2;wf,45,2,1;<BR> <BR> Ea(i)=energy(1)<BR>
Eb(i)=energy(2)<BR> Ec(i)=energy(3)<BR></FONT></DIV>
<DIV><FONT face=Arial size=2>the pertinent output:</FONT></DIV>
<DIV><FONT face=Arial size=2>
T RS
EA
EB
EC </FONT></DIV>
<DIV><FONT face=Arial size=2> 0.0
6.5 -2016.070571 -2016.069385
-2016.070571 <BR> 180.0 6.5
-2016.071635 -2016.069526
-2016.069526 </FONT></DIV>
<DIV><FONT face=Arial size=2>so one can see at 0 degrees (HCN-Ga) Ea & Ec
are degenerate so they are the two Pi states and Eb is the sigma state.
Also the Pi is lower than the sigma which is correct.</FONT></DIV>
<DIV><FONT face=Arial size=2>but at 180 degrees (Ga-HCN) now Eb & Ec are
degenerate, so they are the Pi states. Ea is the sigma state and it is
predicted to be lower in energy which is correct.</FONT></DIV>
<DIV><FONT face=Arial size=2>For simple linear geometries it is easy to pick out
the switching of the labeling, but when the states cross at nonlinear geometries
i don't know how to maintain a consistent labeling.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I've tried looking at the CI vectors:</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>(HCN-Ga)</FONT></DIV>
<DIV><FONT face=Arial size=2> CI vector for state symmetry
1<BR> ------------------------------</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2> 0+ 0
1.0000000 0.0000000<BR> +0 0
0.0000000 1.0000000</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2> TOTAL
ENERGIES
-2016.07057096 -2016.06938539</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2> CI vector for state symmetry
2<BR> ------------------------------</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2> 00 +
1.0000000</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2> TOTAL
ENERGIES
-2016.07057096<BR></DIV>
<DIV>(Ga-HCN)</DIV>
<DIV> </DIV>
<DIV> CI vector for state symmetry
1<BR> ------------------------------</DIV>
<DIV> </DIV>
<DIV> 0+ 0 1.0000000
0.0000000<BR> +0 0 0.0000000
1.0000000</DIV>
<DIV> </DIV>
<DIV> TOTAL
ENERGIES
-2016.07163470 -2016.06952643</DIV>
<DIV> </DIV>
<DIV> CI vector for state symmetry
2<BR> ------------------------------</DIV>
<DIV> </DIV>
<DIV> 00 + 1.0000000</DIV>
<DIV> </DIV>
<DIV> TOTAL
ENERGIES
-2016.06952643<BR><BR>but they don't tell me much.</DIV>
<DIV> </DIV>
<DIV>Any help would be appreciated.</DIV></FONT>
<DIV><FONT face=Arial size=2>___________________________<BR>Jeremy
Merritt<BR>Graduate Student, Roger Miller lab<BR>University of North
Carolina<BR>Chapel Hill</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial
size=2>Voice:919-962-1579<BR>Fax:919-843-6041</FONT></DIV></BODY></HTML>