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Dear Dr. Lu,
Recently I have been doing some Franc-Condon calculations in Gaussian, trying to resolve the vibronic spectra of different molecules. However, for some of them, using a PCM model, I have encountered an error that does not occur when doing the calculations in a vacuum:
"ERROR: Low progression after class 2. Total convergence = 3.3%.
The vibronic spectrum will likely be unreliable. Stopping".
I think the low-frequency modes are causing this issue, as their shift vector is very large; however, experimental resolution is not sufficient to extract them, so I was thinking about omitting them as suggested in this post , however it is not stated explicitly what is the right input setting for RedDim=Block to work. I tried the RedDim=(ClearLowFreq=100) option; however, the calculation leaves only 60 modes out of 200 then.
I would like to inquire about the correct input scheme for the RedDim=Block options: how should it be written? Alternatively, could you suggest any other approaches for calculating the approximate Franck–Condon spectrum in this case with Gaussian software?
I'm quite new to this and do not know how to push this calculation further. Thank you very much in advance for your help!
Dear Mr. Lu,
I have a trouble calculating Duschinsky matrix in GAUSSIAN. The official GAUSSIAN website states that it is possible to calculate it with
Output=Matrix=JKkeyword (https://gaussian.com/freq/ Examples section), however, when I try to run a calculation with the same keywords as in their website, GAUSSIAN .log file states an error:
ERROR: The following wrong keyword(s) have been found:
OUTPUT=MATRIX=JKHowever, I have managed to get vibronic spectrum with a keyword list like this:
%Chk=DPB_gr.chk
# B3LYP/cc-pvtz Freq(ReadFC,FC,ReadFCHT) NoSymm SCRF(Solvent=Cyclohexane) Geom=Checkpoint Guess=Read
FC simulation of UV absorption spectrum for trans,trans-1,4-diphenyl-l,3-butadiene
0 1
SpecHwHm=400 SpecRes=20 InpDEner=0.133
DPB_ex.chkWhat should I add to my keyword list to get the Duschinsky matrix? I have searched through many pages on the internet, however, I did not find more information regarding this issue. Would be very grateful to get any kind of help regarding this error and thank you in advance for sharing your knowledge.
Dear Mr. Lu,
I am trying to calculate the transition dipole moment between the two excited states with GAUSSIAN software and to extract the transition density between excited states for later calculations (transition charges and other parameters) with Multiwfn. Would this be the right keyword setting for QM calculations in GAUSSIAN?
GAUSSIAN input sample for transition density between states 1 and 3:
td=(singlets,nstates=5,root=1) cam-b3lyp/6-31g(d) density=transition=(3,1)
geom=connectivity iop(9/40=4) out=wfn Thanks in advance for the help!
Hello,
I have done QM calculations on GAUSSIAN with this input:
%chk=CLA_401_rotated.chk
# td=(singlets,nstates=5,root=1) cam-b3lyp/6-31g(d) density=transition=1
geom=(modredundant,connectivity) iop(9/40=4) out=wfnand I want to draw an ESP from transition density. I have managed to draw it using Multiwfn and VMD (using 4.A.13 tutorial in the manual), but I am not sure if it's one of the excited state or the ground state. Is it possible to visualize transition density ESP from these parameters, or only the ground state ESP is achievable? If it is not possible with these parameters, what type of GAUSSIAN input would be needed to get the transition density ESP?
Thank you very much in advance!
Thank you very much for the answer! I have read the "Exploring Chemistry with Electronic Structure Methods", however, this procedure was not explicitly stated there, so I had some doubts. Therefore, I am really grateful for your insights.
Dear Mr. Lu,
I am trying to calculate the dipole moment of an excited state, using "Gaussian" software. My input commands were: "opt freq td=(singlets,nstates=5,root=1) cam-b3lyp/6-31g(d) geom=connectivity" as I wanted to optimize the geometry of S1 state (starting from optimized S0 structure) and calculate the S1 dipole moment of the optimized structure. I am wondering, is this is the correct way to do the excited state dipole moment calculation? Moreover, is the Dipole moment in an output after the last "Population analysis using the SCF Density" the correct dipole moment of the excited state? I have looked for the answers over the Internet, however, information regarding this issue is very limited.
Thank you very much in advance for your help!
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