[molpro-user] how to handle singlet diradical?
mht at mrdlab.icas.ac.cn
Wed Apr 26 10:04:03 BST 2006
Hi, thank you for reply and I really, really appreciate it!
I am not familiar with diradical calculation and it's my first
time, accurately. I am doing some repeating-work. It's only test and
practice on reference JPCA,109,7489-7499,2005.
"The diradical are species with a pair of degenerate molecular orbitals
and two electron." You may easyly find this definition by goole since it's
In the reference, a triplet birdical *ABCD*, could be optged;
But the singlet biradical/diradical couldn't.
Q1: biradical==diradical ?
(English is not my mother language.)
Q2: what's singlet diradical? Do the two electron locate on same atom? on
two orbitals? on one of the pair of degerate orbitals? or else?
Like, **ABCE, or *ABCD* (letf * spin up, the right * spin down)
Q3: when I repeat the reference's sinlet diradical geom just via
multi;occ,16;closed,8;wf,24,1,0;, I got the following orbital, it's
not sound reasonable. What should I do? Thanks again!
Molecular orbitals read from record 2140.2 Type=MCSCF/NATURAL (state
Occupation numbers read from record 2140.2 Type=MCSCF/NATURAL (state
Orbital energies read from record 2140.2 Type=MCSCF/NATURAL (state
Redundancy group numbers read from rec 2140.2 Type=MCSCF/NATURAL (state
DUMP ORBITAL 1.1 AS ORBITAL 1 occ= 2.0000 eig= -20.5886 GROUP=
DUMP ORBITAL 2.1 AS ORBITAL 2 occ= 2.0000 eig= -11.2879 GROUP=
DUMP ORBITAL 3.1 AS ORBITAL 3 occ= 2.0000 eig= -11.2376 GROUP=
DUMP ORBITAL 4.1 AS ORBITAL 4 occ= 2.0000 eig= -1.1611 GROUP=
DUMP ORBITAL 5.1 AS ORBITAL 5 occ= 2.0000 eig= -0.9770 GROUP=
DUMP ORBITAL 6.1 AS ORBITAL 6 occ= 2.0000 eig= -0.7683 GROUP=
DUMP ORBITAL 7.1 AS ORBITAL 7 occ= 2.0000 eig= -0.5973 GROUP=
DUMP ORBITAL 8.1 AS ORBITAL 8 occ= 2.0000 eig= -0.5550 GROUP=
DUMP ORBITAL 9.1 AS ORBITAL 9 occ= 1.9842 eig= -0.4991 GROUP=
DUMP ORBITAL 10.1 AS ORBITAL 10 occ= 1.9791 eig= -0.6989 GROUP=
DUMP ORBITAL 11.1 AS ORBITAL 11 occ= 1.9710 eig= -0.7112 GROUP=
DUMP ORBITAL 12.1 AS ORBITAL 12 occ= 1.3044 eig= -0.2158 GROUP=
DUMP ORBITAL 13.1 AS ORBITAL 13 occ= 0.6978 eig= -0.0936 GROUP=
DUMP ORBITAL 14.1 AS ORBITAL 14 occ= 0.0285 eig= 0.7385 GROUP=
DUMP ORBITAL 15.1 AS ORBITAL 15 occ= 0.0196 eig= 0.6612 GROUP=
DUMP ORBITAL 16.1 AS ORBITAL 16 occ= 0.0152 eig= 1.0523 GROUP=
Frequency information read from record 5400.2
On Sat, 22 Apr 2006, H. -J. Werner wrote:
> It is not possible to to open-shell singlets with rhf or uhf.
> Only high-spin states (single Slater determinants) are possible.
> Use mcscf for open-shell singlets!
> Joachim Werner
> On Sa, 22 Apr 2006, MHT wrote:
> >I met the same problem as following, please see "OCC"
> >"The total number of orbitals must be equal to (elec+spin)/2"
> >does this still work for singlet diradical: _up_, _down_,
> > * To: molpro-user at xxxxxxxxxx
> > * Subject: [molpro-user] singlet diradical
> > * From: ghoffman <ghoffman at xxxxxxxxxxxx>
> > * Date: Mon, 13 Jun 2005 10:14:09 -0400
> > * Sender: owner-molpro-user at xxxxxxxxxxxxxxxxxxxx
> >I need some helpful advice for performing a clculation on a singlet
> >diradical. This is a triatomic species with 16 electrons and Cv symmetry.
> >The two unpaired electrons are in orbitals of different symmetry
> >(1=totally symmetric and 2=antisymmetric with respect to reflection in the
> >symmetry plane). Therefore, the symmetry of the electronic state is 2.
> >Because this is a singlet state then, the command for the Hartree-Fock
> >calculation ought to be:
> >The negative sign, according to the manual, designates that the spins of
> >the two unpaired electrons are opposed. However, with this input (and
> >just about every other one I could think of), the following error message
> >is returned when the calculation crashes:
> > SYMMETRIES FROM ORBITAL RESTRICTIONS AND WF CARD NOT CONSISTENT: 2 2
> >MS2= 0 NOPEN= 2
> > ERROR EXIT
> > CURRENT STACK: MAIN
> >Surely, somebody out there has performed calculations on singlet
> >diradicals. How does one get Molpro to understand the desired electron
> >Thanks in advance.
> >Gerry Hoffman
> >Gerald J. Hoffman
> >Assistant Professor of Chemistry
> >Edinboro University of Pennsylvania
> >Edinboro, PA 16412
> >ghoffman at xxxxxxxxxxxx
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