iOpenShell » Q-Chem specific questions » Changing omega in omegaB97X

Changing omega in omegaB97X

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Author Post
Member
Registered: Feb 2013
Posts: 2
Hi all,

I would like to change the range-separation parameter omega in the omegaB97X functional. When simply writing
$1<\zj&w2$frem
EXCHANGE omegaB97X
OMEGA 100
$1<\zj&w2$fend
the omega-parameter is not changed and Qchem uses the standard parameter instead.

In QChem3.2, this problem could easily be solved by defining the omegaB97X functional explicitly, i.e., by writing
$1<\zj&w2$frem
EXCHANGE GEN
LRC_DFT TRUE
OMEGA 100
$1<\zj&w2$fend
$1<\zj&w2$fxc_functional
C wB97X 1.0
X wB97X 1.0
X HF 0.157706
$1<\zj&w2$fend
instead. In Qchem4.0, however, this trick does not seem to work anymore. Qchem4.0 does no longer recognize wB97X as input for C or X ("Unrecognized correlation functional in RemStrProc").

Does anyone know a workaround that works for Qchem4.0?

Thanks a lot in advance!
Member
Registered: Nov 2007
Posts: 110
Location: Q-Chem Inc.
I just fixed that. We can now tune the omega value with exchange=omegaB97, omegaB97X, omegaB97X-D.
Member
Registered: Feb 2013
Posts: 2
Great! Where can I get the latest version that does allow tuning the omega?
Member
Registered: Nov 2007
Posts: 110
Location: Q-Chem Inc.
This should be Q-Chem release 4.1.1.
Member
Registered: Nov 2016
Posts: 1
I tried to do this in qchem 4.4. However, the omega value still doesn't change. Any suggestions? Thanks!

I used the following input:

$1<\zj&w2$frem
exchange omegaB97X
OMEGA 180
$1<\zj&w2$fend

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iOpenShell » Q-Chem specific questions » Changing omega in omegaB97X