First: as stated before make sure that your Gaussian input files have the checkpoint file defined. So each Gaussian input should have:

%RWF=myrwf

%NoSave

%Chk=mychk -> this line is crucial

Also, make sure that you have a large number of SCF iterations: SCF=(MaxCycle=400) and geometry optimization iterations: Opt(MaxCycle=400).

Now - there are two ways of restarting a Gaussian job, if you specified and saved %chk.

One requires just the Restart keyword, while deleting all the original commands and geometry specification:

%RWF=myrwf

%NoSave

%Chk=mychk

#P Restart

The other one and my preferred requires that you use the same input as in the original file, but add the following commands:

# Geom=Checkpoint Guess=Read

and deleting the geometry specification (but leaving the charge and multiplicity) so it looks something like this:

%RWF=myrwf

%NoSave

%Chk=mychk

#P method/basis-set your_commands

# Geom=Checkpoint Guess=Read

0 1

If you want to do it automatically for a large number of files, a short script or a sed command should be very helpful. I can give you a quick example: let's say that your original input file looks like this:

%RWF=myrwf

%NoSave

%Chk=mychk

#P B3LYP/6-31G* opt=(maxcycle=400)

# scf=(direct,maxcycle=200)

# freq

0 1

C 8.79200 2.92260 17.19580

..... (more xyz coordinates or z-matrix lines)

A simple sed command to add a new line and delete geometry specification would be:

sed "s/freq/freq\n# Geom=Checkpoint Guess=Read/g;/0 1$/q" original_input > restart_input

The first part (before ";") will add a new line "Geom=Checkpoint Guess=Read" after freq command. The second part (after ";") will delete everything after the "0 1" line. Unfotrtunately you will still need to add a blank line to the restart_input file, since Gaussian requires it, but it can be also added automatically using a simple script (or echo command).

Dear Skyler

Continue calculation from the last updated geometry (chk as input file).

Next time increase number of SCF iterations (MaxCycle=N) before running your jobs.

regards,

You need to save the checkpointfile and read-write file and then restart the calculation using these files. In this link http://www.gaussian.com/g_tech/g_ur/k_restart.htm it is explained how to do that and how to automatically delete the read-write file if the calculation finishes properly.

http://www.gaussian.com/g_tech/g_ur/k_restart.htm

Hello Vincente,

I read that guide but it listed that "A restartable job is one for which execution was stopped before completion. Jobs that finish with an error message such as convergence failure or exceeding number of optimization steps require user intervention."

Am I wrong in assuming the link9999 error would fall under convergence failure?

Dear skyler,

Its so simple. just load gaussian output file in gauss view and make a new job from your output. As you know the output file contains the last updated geometry structure of your system.

Hope it helps,

HHA

Thanks Renjith,

I've been doing that Hamed, but I just wanted to see if there was a way of doing it without having to reimport and create new input files. If I had to do the reimporting for a thousand jobs that sucks quiet a bit of time.

First: as stated before make sure that your Gaussian input files have the checkpoint file defined. So each Gaussian input should have:

%RWF=myrwf

%NoSave

%Chk=mychk -> this line is crucial

Also, make sure that you have a large number of SCF iterations: SCF=(MaxCycle=400) and geometry optimization iterations: Opt(MaxCycle=400).

Now - there are two ways of restarting a Gaussian job, if you specified and saved %chk.

One requires just the Restart keyword, while deleting all the original commands and geometry specification:

%RWF=myrwf

%NoSave

%Chk=mychk

#P Restart

The other one and my preferred requires that you use the same input as in the original file, but add the following commands:

# Geom=Checkpoint Guess=Read

and deleting the geometry specification (but leaving the charge and multiplicity) so it looks something like this:

%RWF=myrwf

%NoSave

%Chk=mychk

#P method/basis-set your_commands

# Geom=Checkpoint Guess=Read

0 1

If you want to do it automatically for a large number of files, a short script or a sed command should be very helpful. I can give you a quick example: let's say that your original input file looks like this:

%RWF=myrwf

%NoSave

%Chk=mychk

#P B3LYP/6-31G* opt=(maxcycle=400)

# scf=(direct,maxcycle=200)

# freq

0 1

C 8.79200 2.92260 17.19580

..... (more xyz coordinates or z-matrix lines)

A simple sed command to add a new line and delete geometry specification would be:

sed "s/freq/freq\n# Geom=Checkpoint Guess=Read/g;/0 1$/q" original_input > restart_input

The first part (before ";") will add a new line "Geom=Checkpoint Guess=Read" after freq command. The second part (after ";") will delete everything after the "0 1" line. Unfotrtunately you will still need to add a blank line to the restart_input file, since Gaussian requires it, but it can be also added automatically using a simple script (or echo command).

rerun from where you stopped

When using %oldchk key word in G03 or even G09  the following error message is obtained:

%oldchk=C:\Users\Dr.Ahmd\Desktop\Gaussian Tutorials\01-ac.chk

Error parsing percent card:

QPErr --- A syntax error was detected in the input line.

%oldchk=C:\Users\Dr.Ahmd\Desktop\Gaussia

    '

Last state=""

TCursr= 202 LCursr= 1

Error termination via Lnk1e in C:\G09W\l1.exe at Sat Mar 07 23:07:34 2015.

what  could be done not to recieve such an error message

My hunch is the use of the key word "oldchk".  It may be something I have never used before, but this should do it for you:

%chk=C:\Users\Dr.Ahmd\Desktop\Gaussian Tutorials\01-ac.chk

Just as a side note.  I would make sure I had an unchanged copy of my check point file saved somewhere before using it as you are here.  It will be overwritten, and if there is some odd error generated, all of your previous work will be lost.

Good luck!

Here is a link I used often when first trying to understand Gauss' error codes.  You might find it helpful:

http://www.ace-net.ca/wiki/Gaussian_Error_Messages

They feel a bit cryptic when you first start using Gauss.

if we dont save checkpoint file while making input file, then it will effect the normal simulations or not??

Bartosz Trzaskowski Could you provide a detail description on how to read the checkpoint file. I have tried several times, seems like lacking the expertise.