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From: "Huang, Yiqun" <yiqun.huang@ttu.edu>
To: "nwchem-users@emsl.pnl.gov" <nwchem-users@emsl.pnl.gov>
Date: Thu, 28 Aug 2008 15:24:53 -0500
Subject: [NWCHEM] nwchem-5.0 bug for relaxed odft scan?
Thread-Topic: nwchem-5.0 bug for relaxed odft scan?
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I  encounter a strange problem when running relaxed odft scan for close-she=
ll homolytic dissociation: A2-->A+A.  e,g, ethane--> CH3 +CH3.  The functio=
nal is odft/b3lyp with 6-31G** basis set. The version I used is nwchem 5.0.=
 depending on scan direction (towards dissociation or association) and the =
starting A-A separation, sometimes the overlap between alpha and beta KS or=
bitals are resonable (< 100%), and the dissociation behavior is OK. Sometim=
es it looks like only restricted KS orbitals are used (overlap always =3D10=
0% even if at very large A-A separation such as 8A). especially, if the sca=
n starts at equilibrium geometry of A2, then it always gives 100% alpha and=
 beta overlap through the whole scan. Is someting wrong with the code or I =
need to modify my input file?

I copied the parts of my input file here. And thanks for any help.

yiqun


see below:


dft
odft
MULT 1
xc b3lyp
grid fine; iterations 2000
end
driver
maxiter 2000
end
basis; N library 6-31g**; H library 6-31g**; C library 6-31g**; end

  geometry # DMT
C    0.00000000  0.00000000  0.00000000
N    1.03680829 -1.00277213  0.23300929
N    1.70726738 -0.67642554  1.44830861
H    1.12009190 -0.95578983  2.24084711
H    2.57703126 -1.20132239  1.48291476
H   -0.49338471 -0.22633929 -0.94747797
H   -0.75575598  0.01993930  0.80057821
H    0.48105978  0.97784746 -0.05626057
N   -1.07953585 -5.53178817  0.13760929
N   -1.78823611 -5.80597548  1.35368770
H   -2.66606795 -6.25247931  1.10670415
H   -1.26514207 -6.45320784  1.94698333
C   -0.06690186 -6.53777540 -0.15124477
H   -0.55753498 -7.50194556 -0.31381469
H    0.46622639 -6.24941535 -1.05865023
H    0.67004113 -6.66107293  0.66537143
      end


geometry adjust
             zcoord
               bond  2 9    5.0 NN constant
             end
           end
           task dft optimize

the remaining parts are omiited.