scf energy error
Clicked A Few Times
11:37:30 AM PDT - Thu, Jun 11th 2015
Hi,

I have been trying to do intial geometry optimization using Hartree Fork. But i am getting following error:-

scf_gradient: scf energy failed 0
scf_gradient: scf energy failed        0


My input file is as below:-

echo

start molecule

title "Title"
charge 0

geometry units angstroms print xyz autosym
  C        0.07866        0.40142       -0.82732

  C       -0.60818        1.61063       -0.19064

  C        1.24006        0.39967       -0.52411

  C        2.18721        1.22161        0.21145

  C        4.36093        0.59709       -0.81391

  C        3.63280        1.36103       -0.04907

  C        5.85123        0.67804       -1.14040

  C        6.36058        1.60327       -0.56986

  C       -0.21625        2.55446        0.61753

  C       -0.64573        3.89660        0.56984

  C        1.29627        2.51292        0.79959

  C        2.12037        3.68559        0.15598

  C        4.36286        2.52889        0.67172

  C        3.61084        3.79070        0.35810

  C        5.91006        2.62676        0.32901

  C        6.37305        3.97059        0.38887

  C       -0.16779        5.10116        0.48344

  C       -1.07619        6.28431        0.36200

  C        1.25810        5.09661        0.03307

  C        2.21933        6.17891        0.17708

  C        4.35245        5.05281       -0.17047

  C        3.41931        6.14721        0.13814

  C        5.79802        5.14018        0.33257

  C        6.70052        6.35387        0.29410

  O        4.38857        4.89709       -1.60159

  H        4.74714        5.73328       -1.95382

  O        1.59576        4.21602       -1.06928

  O        4.30789        2.39250        2.09226

  H        3.96236        1.50612        2.30007

  O        1.84117        1.45787        1.58335
end

basis
 * library 6-311++G** file /nodes/c3-7-1/nwchem-6.1.1-src/src/basis/libraries/
end

task scf optimize

Kindly let me know what needs to be done to fix the issue.

Thanks

Gets Around
3:44:34 PM PDT - Thu, Jun 11th 2015
I would suggest 3 things:

1) Do a preliminary geometry optimization with a smaller basis set, unless you have already tried that and it finds the wrong local minimum
2) Use spherical functions with "basis spherical"
3) Increase the maxiter for scf solution, e.g.

scf
 maxiter 999
end


Before any "task scf".

EDIT: and you may need more geometry steps too, e.g.

driver
 maxiter 999
end


before your optimization task(s).

Clicked A Few Times
5:30:39 PM PDT - Thu, Jun 11th 2015
Thanx, I will try these options.


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