This year, the Nobel Prize for Chemistry has a special flavor for computational biochemists, as the Swedish Academy has decided to recognize the creators of Quantum Mechanics/Molecular Mechanics hybrid methods. Levitt and Warshel developed the first computational simulation of a protein, back in 1975, whereas Karplus and his group developed the well-known CHARMm force-field and molecular dynamics code. I am very glad to see Warshel recognized as the towering giant he really is (in spite of his short stature). He is a very warm and likeable fellow, always eager for a good discussion on the merits (and demerits) of a scientific proposal. He does have, however, a singular lack of patience for bullshit, and a peculiar disregard for diplomatic niceties ....
Warshel's parents were Polish Jews who left Europe for Palestine before World War II to join a kibbutz. He attributes part of his peculiar temper to the circumstances of growing up in such an utopian socialist community in the 1940's, before the Israeli War of Independence. Lying and "truth embellishment" were very strongly frowned upon, and one was expected to be able to withstand withering criticism whenever warranted. His BS-detector is therefore quite over-calibrated, and he takes no prisoners when arguing against a wrong-headed argument. Warshel's abrasive style is well-known in the computational chemistry, as are is frequent controversies with other workers.
He also told me one of the best jokes I know... He presented it as a real tale of his uncle's exploits as an officer in the Polish Army. here it goes:
During on of his official leaves, his uncle went to a brothel. After the "job" had been done, he got up to get dressed and leave. The prostitute the asked: "What about the money, sir?". And he replied: "An officer never accepts money, my lady"
Wednesday, October 9, 2013
Friday, July 5, 2013
Gamess (US) frequently asked questions Part 5: "THE VIBRATIONAL ANALYSIS IS NOT VALID"
Gamess (US) and Firefly by default assume geometric convergence has been achieved when the maximum gradient is below 1e-4 and the RMS gradient is smaller than 1/3 of the maximum gradient. This convergence criterion may be changed by the user with
$STATPT OPTTOL=<your desired convergence criterion> $END
It is well known that the vibrational analysis is strictly valid mathematically when the Hessian is computed in true stationary points (i.e when the gradient is exactly equal to zero). If the maximum gradient is sufficiently close to zero, the vibrational analysis (although not absolutely correct) is still close enough to the "true" solution for all practical purposes.
This introduction brings us to today's FAQ. A recurring question in both the Gamess-US list and the Firefly forums concerns the message often printed by the program after a vibrational analysis:
*THIS IS NOT A STATIONARY POINT ON THE MOLECULAR PES THE VIBRATIONAL ANALYSIS IS NOT VALID*
This message arises from the way gradients are analyzed by Gamess: gradients are originally computed in one set of coordinates (cartesian coordinates, I believe) , and then transformed into the coordinate system specified by the user. Optimizations stop when the "transformed gradient" lies below OPTTOL, but Gamess uses the original, non-transformed, gradient to decide whether to consider the geometry as a stationary point on the molecular PES. Therefore, if the geometry is converged, the scary message in capital letters above may be safely disregarded. When in doubt, simply decrease your OPTTOL value, continue the optimization and re-compute the hessian.
$STATPT OPTTOL=
It is well known that the vibrational analysis is strictly valid mathematically when the Hessian is computed in true stationary points (i.e when the gradient is exactly equal to zero). If the maximum gradient is sufficiently close to zero, the vibrational analysis (although not absolutely correct) is still close enough to the "true" solution for all practical purposes.
This introduction brings us to today's FAQ. A recurring question in both the Gamess-US list and the Firefly forums concerns the message often printed by the program after a vibrational analysis:
*THIS IS NOT A STATIONARY POINT ON THE MOLECULAR PES THE VIBRATIONAL ANALYSIS IS NOT VALID*
This message arises from the way gradients are analyzed by Gamess: gradients are originally computed in one set of coordinates (cartesian coordinates, I believe) , and then transformed into the coordinate system specified by the user. Optimizations stop when the "transformed gradient" lies below OPTTOL, but Gamess uses the original, non-transformed, gradient to decide whether to consider the geometry as a stationary point on the molecular PES. Therefore, if the geometry is converged, the scary message in capital letters above may be safely disregarded. When in doubt, simply decrease your OPTTOL value, continue the optimization and re-compute the hessian.
Wednesday, June 26, 2013
Gamess (US) frequently asked questions Part 4: The rungms script
Third guest post by Kirill Berezovsky (Petrozadovsk State University).
Gamess (US) is run though a script provided in the installation package. This script MUST be adapted by the user. The rungms-script below has been adapted to be used with the Gamess (US) installation described in earlier posts. Happy computing :-)
Gamess (US) is run though a script provided in the installation package. This script MUST be adapted by the user. The rungms-script below has been adapted to be used with the Gamess (US) installation described in earlier posts. Happy computing :-)
RUNGMS script
#!/bin/csh
set SCR=/scr/$USER
set USERSCR=~$USER/scr
set GMSPATH=/usr/local/gamess
set JOB=$1
set VERNO=$2
if ($VERNO == cpu) set TARGET=mpi
if ($VERNO == gpu) set TARGET=ga
if (null$VERNO == null) set VERNO=cpu
set master=`hostname`
printf "\n * Started at: `date`"
set DSK=`df -m $SCR | awk 'NR==2{print$4}'`
printf "\n * Available disk space: $DSK MB"
printf "\n * Temporary files in: $SCR and in $USERSCR\n\n"
limit stacksize 8192
if ($JOB:r.inp == $JOB) set JOB=$JOB:r
if (-e $JOB.inp) then
cp $JOB.inp
$SCR/$JOB.F05
else
echo
"Input file $JOB.inp not found"
exit 4
endif
source $GMSPATH/gms-files.csh
if (-e $HOME/.gmsrc) source $HOME/.gmsrc
set ngddi=`grep -i '^ \$GDDI' $SCR/$JOB.F05 | grep -iv
'NGROUP=0 ' | wc -l`
if ($ngddi > 0) then
set
GDDIjob=true
echo
"This is a GDDI run, keeping various output files on local disks"
set echo
setenv OUTPUT $SCR/$JOB.F06
setenv PUNCH $SCR/$JOB.F07
unset echo
else
set
GDDIjob=false
endif
if ((-e $PUNCH) || (-e $MAKEFP) || (-e $TRAJECT) ||
(-e $RESTART) ) then
echo "Please
save, rename, or erase these files from a previous run:"
echo
" $PUNCH,"
echo
" $TRAJECT,"
echo
" $RESTART, and/or"
echo
" $MAKEFP,"
echo
"and then resubmit this computation."
exit 4
endif
#----------------------------------------------------------------------
if ($TARGET == mpi) then
set NCPUS=`grep
cores /proc/cpuinfo | wc -l`
echo " * CPU
cores: $NCPUS "
echo " * GPU devices: not used"
echo " "
setenv TRAJECT $USERSCR/$JOB.trj
setenv RESTART
$USERSCR/$JOB.rst
setenv INPUT
$SCR/$JOB.F05
setenv PUNCH
$USERSCR/$JOB.dat
if ( -e
$TRAJECT ) rm $TRAJECT
if ( -e $PUNCH ) rm $PUNCH
if ( -e $RESTART ) rm $RESTART
setenv
LD_LIBRARY_PATH /opt/intel/impi/4.0.2.003/intel64/lib:$LD_LIBRARY_PATH
set path= (
/opt/intel/impi/4.0.2.003/intel64/bin $path )
mpdboot
mpiexec -n
$NCPUS $GMSPATH/gamess.$VERNO.x
mpdallexit
cp $PUNCH .
endif
#----------------------------------------------------------------------
if ($TARGET == ga) then
set PPN=1
set NCPUS=1
@ NPROCS =
$NCPUS
setenv HOSTFILE
$SCR/$JOB.nodes.mpd
if (-e
$HOSTFILE) rm $HOSTFILE
touch $HOSTFILE
echo `hostname`
>> $HOSTFILE
set NNODES=1
setenv PROCFILE
$SCR/$JOB.processes.mpd
if (-e
$PROCFILE) rm $PROCFILE
touch $PROCFILE
echo "-n
$NPROCS -host `hostname` $GMSPATH/gamess.$VERNO.x" >> $PROCFILE
set
path=(/opt/intel/impi/4.0.2.003/intel64/bin $path)
setenv
I_MPI_WAIT_MODE enable
setenv
I_MPI_PIN disable
setenv
I_MPI_DEBUG 0
setenv
I_MPI_STATS 0
setenv
I_MPI_DEVICE sock
setenv
I_MPI_NETMASK ib0
setenv
LD_LIBRARY_PATH /opt/intel/impi/4.0.2.003/intel64/lib:$LD_LIBRARY_PATH
setenv
LD_LIBRARY_PATH
/opt/intel/composerxe-2011.4.191/compiler/lib/intel64:$LD_LIBRARY_PATH
setenv
LD_LIBRARY_PATH /opt/intel/composer_xe_2013.0.079/mkl/lib/intel64:$LD_LIBRARY_PATH
setenv
MKL_SERIAL YES
setenv
MKL_NUM_THREADS 1
setenv
LD_LIBRARY_PATH /usr/local/cuda/lib64:$LD_LIBRARY_PATH
setenv
GMS_CCHEM '1'
@ NUMGPU=1
setenv CCHEM
'devices=0;memory=4g'
echo " * CPU cores: `grep cores /proc/cpuinfo | wc -l` "
echo " * GPU devices:
$NUMGPU (with settings: $CCHEM)"
echo "
"
chdir $SCR
set echo
mpdboot
--rsh=ssh -n $NNODES -f $HOSTFILE
mpiexec
-configfile $PROCFILE < /dev/null
mpdallexit
unset echo
rm -f $PROCFILE
endif
#----------------------------------------------------------------------
echo ----- accounting info -----
if ($GDDIjob == true) cp $SCR/$JOB.F07 ~/scr/$JOB.dat
echo Files used on the master node $master were:
ls -lF $SCR/$JOB.*
rm -f
$SCR/$JOB.F*
if (-e $SCR/$JOB.V84) mv $SCR/$JOB.V84 $USERSCR
if (-e $SCR/$JOB.V80) rm -f $SCR/$JOB.V*
if (-e $SCR/$JOB.TEMP02) rm -f $SCR/$JOB.TEMP*
if (-e $SCR/$JOB.orb) mv $SCR/$JOB.orb $USERSCR
if (-e $SCR/$JOB.vec) mv $SCR/$JOB.vec $USERSCR
if (-e $SCR/$JOB.mol) mv $SCR/$JOB.mol $USERSCR
if (-e $SCR/$JOB.molf) mv $SCR/$JOB.molf $USERSCR
if (-e $SCR/$JOB.mkl) mv $SCR/$JOB.mkl $USERSCR
if (-e $SCR/$JOB.xyz) mv $SCR/$JOB.xyz $USERSCR
ls $SCR/${JOB}-*.cube > $SCR/${JOB}.lis
if (! -z $SCR/${JOB}.lis) mv $SCR/${JOB}*.cube
$USERSCR
rm -f $SCR/${JOB}.lis
ls $SCR/${JOB}-*.grd > $SCR/${JOB}.lis
if (! -z $SCR/${JOB}.lis) mv $SCR/${JOB}*.grd $USERSCR
rm -f $SCR/${JOB}.lis
ls $SCR/${JOB}-*.csv > $SCR/${JOB}.lis
if (! -z $SCR/${JOB}.lis) mv $SCR/${JOB}*.csv $USERSCR
rm -f $SCR/${JOB}.lis
if ($TARGET == mpi) then
set
nnodes=`wc -l $HOSTFILE`
set
nnodes=$nnodes[1]
@ n=1
set
master=`hostname`
set
master=$master:r
while ($n
<= $nnodes)
set
host=`sed -n -e "$n p" $HOSTFILE`
set
host=$host[1]
if ($host
!= $master) then
echo
Files used on node $host were:
ssh
$host -l $USER "ls -l $SCR/$JOB.*"
ssh
$host -l $USER "rm -f $SCR/$JOB.*"
endif
@ n++
end
rm -f
$HOSTFILE
if
($?I_MPI_STATS) then
if
($I_MPI_STATS > 0) mv $SCR/stats.txt ~/$JOB.$NCPUS.stats
endif
endif
date
time
exit
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