how to run PES (relaxed and rigid) of excited states using Gaussian ?
You can use "scan" keyword for rigid scan and "opt=modredundant" for relaxed scan. For example, using "# PBE1PBE/6-31G* opt=modredundant TD(nstates=5,root=2)" and properly specifying scan rule after molecular geometry field, you can perform relaxed scan at TD-PBE0/6-31G* level for the second excited state.
Mr Bharadvaja,
By means of Gaussian's IOPs: http://gaussian.com/iops/.
You can use "scan" keyword for rigid scan and "opt=modredundant" for relaxed scan. For example, using "# PBE1PBE/6-31G* opt=modredundant TD(nstates=5,root=2)" and properly specifying scan rule after molecular geometry field, you can perform relaxed scan at TD-PBE0/6-31G* level for the second excited state.
thanks @ Dr Tian Lu and Dr Ivanova....
i took an various diatomic molecules as exercise and found in all of them SCF energy, optimization energy of 1st excited state and excitation energy and geometry corresponding to minimum energy obtained using (a) and (b) differed. this is example of CO (carbon monoixde)
0 1
c 0.000000 0.000000 -0.078476
o 0.000000 0.000000 0.7278476
1 2 s 50 0.02
(a) opt b3lyp/6-31g* td(nstates=5)
(b) b3lyp/6-31G* opt=modredundant TD(nstates=5 root=1)
both (a) and (b) are essentially doing the same ....by default (a) prints optimised excited state energy and various parameters of first excited state while (b) does scan over various bondlenghts which in my problem included minimum obtained from (a)
further to my surprise the scanned output using below too differed. the input and output files are attached for below mentioned jobs
c # opt=modredundant td=(nstates=6) b3lyp/6-311g(d) test
d # opt=modredundant td=(nstates=6,root=1) b3lyp/6-311g(d) test
distance energy (d) energy (c)
1.2263230000 -113.0496497630 -113.0496497630
1.2463230000 -113.0497260700 -113.0497260700
1.2663230000 -113.0489641070 -113.0496497630 ...
. ....
1.3463230000 -113.0397412520 -113.0498762080
1.3663230000 -113.0363353970 -113.0498929930
pl explain the reasons or what gaussian does ?
how to assess the correct geometry when we r getting 2 minima in (c)
thanks for patient reading.
- Badges
- Science topic
- Similar topics
- Biological Science
- Kinesiology
- Running