Three ways to do it:

1. "Restart" restarts a previously-failed optimization via (checkpoint file) .chk and a previously-field frequency via (read-writ file) .rwf. G09 and G16 can do the restart an analytic freq work if it can find out the .rwf file (If you have used %rwf=X.rwf ), otherwise you have to start it from the beginning.

For restart, Keep (%chk, %mem, %nprocshared, %rwf) but use "Restart keyword" in the route section.

2. This will restart optimization from the last geometry from the .chk and then start the frequency calculations from the beginning.

Take a copy of the original input file and add:

#Geom=Checkpoint guess=read (Reads the initial guess from the .chk and it's a way to switch from one basis to another) or

#Geom=AllCheckpoint (Reads the geometry, charge, multiplicity and title from the .chk and it's used to start at a different level).

3. You can open the output file (.log) in gaussview, save the last geometry and then run gaussian again without any OPT, but just do single-point energy + frequency calculations. This will also start the frequency calculations from the beginning.

Best,

Tahereh

Titon Saha , A calculation can be started using information from the checkpoint file (.chk) by including different commands in the route card, for example:

SCF=Restart

Restart a SCF calculation from the checkpoint file. This is normally used when an SCF calculation failed finish for some reason.

Freq=Restart

Restarts a numerical frequency calculation which did not complete. Analytic frequency calculations cannot be restarted.

Opt=Restart

Restarts a geometry optimization which did not complete.

...etc

Titon Saha, If a geometry optimization is terminated before completion due to an external factor, you can resume it simply by adding the Restart option to the Opt keyword into the route section of the original job, as in this example:

%Chk=myfile

# Opt=Restart

The Opt=Restart option always begins from the last completed point in the previous optimization.

If the Opt keyword originally had other options, in most cases you can simply add Restart to the existing set:

%Chk=myfile

# Opt=(QST2,Restart) …

Three ways to do it:

1. "Restart" restarts a previously-failed optimization via (checkpoint file) .chk and a previously-field frequency via (read-writ file) .rwf. G09 and G16 can do the restart an analytic freq work if it can find out the .rwf file (If you have used %rwf=X.rwf ), otherwise you have to start it from the beginning.

For restart, Keep (%chk, %mem, %nprocshared, %rwf) but use "Restart keyword" in the route section.

2. This will restart optimization from the last geometry from the .chk and then start the frequency calculations from the beginning.

Take a copy of the original input file and add:

#Geom=Checkpoint guess=read (Reads the initial guess from the .chk and it's a way to switch from one basis to another) or

#Geom=AllCheckpoint (Reads the geometry, charge, multiplicity and title from the .chk and it's used to start at a different level).

3. You can open the output file (.log) in gaussview, save the last geometry and then run gaussian again without any OPT, but just do single-point energy + frequency calculations. This will also start the frequency calculations from the beginning.

Best,

Tahereh

Thanks a lot, Melek Hajji & Seyedeh Tahereh Hosseini .

Firstly, I've never saved '.rwt' files for my calculation before. In that case, can I start from .chk file only?

Secondly, Seyedeh Tahereh Hosseini is there any option to restart both optimization and frequency at a time (from the endpoint) other than your 2nd & 3rd option?

My job is an optimization+frequency job, that's why I am very confused about it.

I'm attaching my chk, log & gjf files of the related task. I'll be very glad if you clarify me/if you can attach the file by adding the required keywords.

I must say, the geometry optimization can be restarted from the .chk file as usual and the one-step computation, such as Analytic frequency calculations, can be restarted from .rwf file and based on my information, without .rwf you can't restart freq calculation. As I said, you can just restart optimization from the last geometry from the .chk and then start the frequency calculations from the beginning.

For your other job:

(You should note that if you anticipate that a job may need restarting at some point, then you can assign a name to the read-write file (.rwf) in the original job:

%RWF=/path/filename.rwf

Also, to restart a job from .rwf, you need to know where the file is from previous run and If you don’t specify the rwf file path then you cannot restart it from where it left. For example, .chk is in the directory where you submitted the job but .rwf is in /scratch/yourid/jobid/. You have to move *.rwf file from /scratch/youris/jobid/ to /scratch/yourid/ to restart the previous job from that .rwf file).

Sample input file for freq and opt job:

This link will be useful for you, it's about restarting Analytic and Numerical frequency calculations and for full details, you can use Gaussian user’s reference.

https://gaussian.com/faq2/

I hope you find it helpful.