Gaussian 16 Calculation Task Continuation

1. Geometry Optimization

Prerequisite: A checkpoint file (.chk) from a previous calculation is required.

Continuation Method: Add opt=restart to the route section.

Example

Original input file:

%chk=xxx.chk
#p opt=QST2 ...

Continuation input file:

%chk=xxx.chk
#p opt=(QST2,restart) ...

Additional Notes:

1. If there are other options after the opt keyword in the original input file, you can simply add restart.
2. If the original input file contains CalcFC or RCFC options, you can ignore them in the continuation input file and use the restart option directly.
3. To resume geometry optimization from a specific step, use the step=n option in the geom keyword. For example:

   %oldchk=xxx.chk
   %chk=new_xxx.chk
   #p opt geom=(allcheck,step=6) guess=read
   

2. IRC

Prerequisites:

• The calculation is not finished.
• Or the calculation is finished, but you want to continue the calculation with more steps.

Continuation Method: Use the IRC=restart command.

Examples

For unfinished calculation:

%chk=xxx.chk
#p IRC=restart ...

Calculation finished, adding more steps:

%chk=xxx.chk
#p IRC=(restart,maxpoint=20) ...

3. Vibrational Analysis

Prerequisites:

• In addition to the .chk file, you also need the .rwf file.
• The .rwf file is located in the Scratch folder.

Continuation Method:

1. Add the %rwf section to the input file to specify the path to the .rwf file.
2. Use the restart keyword.

Example

%chk=xxx.chk
%rwf=/path/filename.rwf
# restart

Obtaining the .rwf File Path:

The .rwf file name is written at the beginning of the .log or .out output file, for example:

Entering Gaussian System, Link 0=g16
Initial command:
/home/wangzhe/g16/l1.exe "/home/wangzhe/g16/Scratch/Gau-73779.inp" -scrdir="/home/wangzhe/g16/Scratch/"
Default is to use a total of  16 processors:
                              16 via shared-memory
                               1 via Linda
Entering Link 1 = /home/wangzhe/g16/l1.exe PID=     73781.

In this example, the path to the .rwf file is:

/home/wangzhe/g16/Scratch/Gau-73781.rwf