TURBOMOLE Users Forum
TURBOMOLE Modules => Ridft, Rdgrad, Dscf, Grad => Topic started by: martijn on January 26, 2009, 02:46:28 PM
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Hi,
I am calculating the energy of the lowest triplet state of a silica cluster with BLYP (in C1) but while the SCF converges (after restart) I get the following occupation at the end (using eiger):
453. a 227 a -0.125221 H = -3.407 eV
452. b 226 a -0.156735 H = -4.265 eV
451. a 226 a 1.000 -0.213428 H = -5.808 eV
450. b 225 a -0.254862 H = -6.935 eV
449. b 224 a 1.000 -0.268082 H = -7.295 eV
448. b 223 a 1.000 -0.268131 H = -7.296 eV
447. a 225 a 1.000 -0.268395 H = -7.303 eV
And the following error message (also from eiger):
HOMO-LUMO Separation
HOMO: 451. a 226 a -0.21342759 H = -5.80766 eV
LUMO: 450. b 225 a -0.25486211 H = -6.93515 eV
Gap : -0.04143452 H = -1.12749 eV
!! WARNING: HOMO-LUMO Gap is negativ !!
I thus seem to get some triplet excited state rather than the desired lowest triplet. How can I manually change the occupation such that the HOMO ends up being orbital 450 instead of 451?
Thanks in advance,
Martijn
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Hi,
if you occupy orbital 450 (a beta orbital) instead of 451 (an alpha orbital), you would get a singlet again.
A hole in the occupation just means that you are not in the ground state - but if the singlet is more stable than the triplet, this is normal.
To check if there is a more stable triplet, you could try to use $fermi. Add the keyword as described in the manual or from within define, but add nue=2 to the $fermi line in the control file (nue="number of unpaired electrons"). This option works with Turbomole 5.10 and newer.
$fermi tmstrt=350.00 tmend=150.00 tmfac=0.98 hlcrt=1.0E-01 stop=1.0E-03 nue=2
and rerun ridft.
You can, of course, always edit the occupation by hand in the control file and run an energy calculation.
Regards,
Uwe