Singlet/Triplet Crossing Point

[Todd J. Martinez]

Hello,
   Does anyone have an example input deck for finding a minimal energy
   crossing between states of different spin symmetry, e.g. singlet and
   triplet?  Tha manual implies that this is possible (indeed it should not be
   much different from a conical intersection search), and I can easily get
   molpro to state-average over states of different spin symmetry.  But I
   cannot figure out the correct state label in the CPMCSCF directive...  For
   example, if I solve for the lowest singlet and the lowest triplet, the
   input to multi looks like [CAS(2/3) of ethylene]:

   NELEC=16;
   SYMMETRY=[1,1];
   SPIN=[0,2];
   STATE=[1,1];
   occ=10;
   closed=7;
   MULTI
   CONFIG,det;

   This gets the state average of the lowest singlet and triplet.  Now, we
   also need to solve the CPMCSCF eqns.  The following two linesassume that
   the singlet and triplet will be states 1 and 2 of spatial symmetry 1:

   CPMCSCF,GRAD,2.1,RECORD=5100.1
   CPMCSCF,DGRAD,1.1,2.1,RECORD=5102.1

   But this is not right.  How do we denote the "state symmetry?"  I tried
   1.1.1 and 1.1.2, thinking perhaps the labels were
   statenumber.spatialsymmetry.statesymmetry, but that got me nowhere.  Any
   ideas?
-Todd
-- 
E-Mail: tjm at spawn.scs.uiuc.edu   U.S. Mail: Todd Martinez
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