i restarted an opt +Freq job with the keywords opt=restart, pop=nboread... but the output file do not contain any NBO section as it should ( i an need the natural population analysis) ! can i get it from the chk file? is there any othar to avoid re run the process
In the following I assume you calculation finished correctly and the geometry optimization was achieved as well as the frequency calculation.
‘Nboread’ requires a further section starting with $nbo. Did you include it in the command file containing the opt=restart keyword?
In any case, you can carry out a rather quick nbo calculation using the chk file containing the optimized geometry.
$oldchk=
$chk=< a new chk file for nbo calc>
#p functional chkbasis geom=allcheck guess=read pop=(full,nboread) …
$nbo
$end
Dear Messaadia Sabir ,
First of all, do you have NBO program? is it well installed and in communication with gaussian?
It is an important check before trying to solve your problem as NBO is not free (You could have a look on Janpa Project for this purpose if you absolutely need it).
Then, I encountered recurrent problems trying to perform optimization with NBO following by "FREQ" with the following instructions: "POP=SAVENBO" or "POP=NBO6READ" (I have NBO 7.0 program). Whereas, I don't have any issues with the non-use of "FREQ" keyword.
I totally agree with Prof. Massimiliano Arca and I'm happy to know how to circumvent this problem with the given answer. Otherwise, I usually perform a OPT + FREQ calculation with Gaussian and then perform another one with POP=SAVENBO or POP=NBO6READ with the optimized geometry and "SP NOSYMM" to have a NBO analysis at the same level of theory of course.
Hello Messaadia Sabir ,
I suggest you run optimization calculation instead of opt+freq.
Then, add pop=(full,nbo) to the command line.
# opt 6-31+g(d,p) pop=(full,nbo) geom=connectivity
NB: You can use your choice basis set.
The log file will give the natural bond analysis details.
Cheers.
Thank you all Massimiliano Arca Corentin Lefebvre Eric Akintemi for your answer
i will try you suggestions
sincerely
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