The SHUT command is not a keyword, instead it is a small command script that can be used to send a message to a running MOPAC job to instruct it to shut down in a tidy manner, and to generate restart and density files. When MOPAC reads the message, it increases the apparent CPU time by 10,000,000 seconds (over 100 days). This exceeds any reasonable job time, so MOPAC behaves as if it had run out of time.
Caveat: Because the SHUT command stops a job in a tidy manner, it will not stop a job if a time-consuming process such as an SCF is running, instead it will wait until the process has finished. This means that if the process needs a lot of time to complete, it might appear that SHUT has not worked. SCF calculations are one of the most time-consuming steps, so if a 1SCF job is run, the job will normally go to completion even if the SHUT command is issued.
How SHUT works
When a MOPAC job is running, it periodically checks a file called <name>.end. At the start of the run, <name>.end is empty, that is, it is a file with nothing in it. While <name>.end has nothing in it, the job will continue normally. If there is any text at all in <name>.end the next time MOPAC checks the file it will increase the apparent CPU time by 107 seconds. SHUT simply puts some text into <name>.end. The two scripts given below.
For WINDOWS: Copy the script below and put it into a file called shut.cmd. Put shut.cmd into a folder in the PATH. shut.cmd is used at the command prompt in the folder where the job is running. To use it to shut down a job called <file>.mop, issue the command "shut <file>" , e.g.:
M:\> shut crambin
would issue the SHUTDOWN command to the running job crambin.
Start of WINDOWS shut.cmd script:
echo off
if exist %1.dat goto dat
if exist %1.mop goto mop
if exist %1.arc goto arc
echo The file %1.mop, %1.dat, or %1.arc does not exist in this folder
goto end
:dat
copy %1.dat %1.end
goto end1
:arc
copy %1.arc %1.end
goto end1
:mop
copy %1.mop %1.end
:end1
echo shutdown command issued to %1
:end
For Mac and Linux: Copy the script below and put it into a file called shut.csh. Change permissions on shut.csh to make it executable (chmod +x shut.csh) Put shut.csh into a directory in the PATH, or alias it in the .bashrc or .cshrc scripts. shut.csh is used at the command prompt in the directory where the job is running. To use it to shut down a job called <file>.mop, issue the command "shut <file>" , e.g.:
~ > shut crambin
or
~ > shut crambin.mop
would issue the SHUTDOWN command to the running job crambin.
#!/bin/sh
#
# SHUTDOWN command
# Remove last four characters of file.
#
file=$1
if [ `expr "$file" : ".*.mop"` -gt 0 ]; then file=${file:0:`expr $file : '.*'` -4}; fi
if [ `expr "$file" : ".*.out"` -gt 0 ]; then file=${file:0:`expr $file : '.*'` -4}; fi
if [ `expr "$file" : ".*.dat"` -gt 0 ]; then file=${file:0:`expr $file : '.*'` -4}; fi
if [ `expr "$file" : ".*.arc"` -gt 0 ]; then file=${file:0:`expr $file : '.*'` -4}; fi
echo Shutdown > $file.end
The second form, ~ > shut crambin.mop, is useful if the name is long and has been supplied to "shut.csh" using "copy and paste."