Adaptive tempering floating point exception

From: Stober, Spencer T (spencer.t.stober_at_exxonmobil.com)
Date: Fri Oct 18 2013 - 13:21:03 CDT

Does anyone have an idea why I receive a floating point exception with adaptive tempering. Please see below.

Thanks, Spence

From: Stober, Spencer T
Sent: Friday, September 27, 2013 10:56 AM
To: namd-l_at_ks.uiuc.edu
Subject: Adaptive tempering floating point exception

Greetings,

If I run this simulation (see config file below) with adaptTempMD=off, it runs without problems. If I set adaptTempMD=on it stops on the first time-step where adaptive tempering becomes active (adaptTempFirstStep) and the error "Floating point exception" appears in standard output.

I am using the precompiled NAMD 2.9 x86_64 multicore binary on a 16 core workstation. I have tried only one core or all 16 and still have the error. I have also tried this under NPT and NVT, both also have the error.

Hopefully, I have made a silly mistake in the configuration file.

Thanks in advance, Spence

##########################################
coordinates 512_slab_ua.pdb
structure 512_slab_ua.psf

#########################################
set output md_out_anneal_initial
set input min
set temperature 373.15
set pressure 1.0135

parameters master_trappe_ua.par

bincoordinates ${input}.coor
binvelocities ${input}.vel
extendedSystem ${input}.xsc

# Force-Field Parameters (for TRAPPE_UA)
paratypecharmm on
exclude 1-3
cutoff 12
switching on
switchdist 11
pairlistdist 16
dielectric 1.0

###############################################################################
# Integrator Parameters (1 fs, gold std) [use 1 1 3 for NVE]
timestep 1
nonbondedFreq 2
fullElectFrequency 4
stepspercycle 20

###############################################################################
# Constant Temperature Control
langevin off
langevinDamping 5
langevinTemp $temperature
langevinHydrogen off

###############################################################################
# Constant Pressure Control (variable volume)
langevinPiston off
langevinPistonTarget $pressure
langevinPistonPeriod 200
langevinPistonDecay 100
langevinPistonTemp $temperature
useGroupPressure yes
useFlexibleCell no
useConstantRatio no
useConstantArea no

###############################################################################
# PME (for full-system periodic electrostatics)
PME yes
PMEGridSpacing 1.0

adaptTempMD on
adaptTempTmin 10
adaptTempTmax 1000
adaptTempBins 1000
adaptTempLangevin on
adaptTempFirstStep 2000
adaptTempLastStep 9000000
adaptTempRandom on

###############################################################################
# Output
outputname $output
dcdfile ${output}.dcd
xstFile ${output}.xst
dcdfreq 1000
xstFreq 1000
binaryoutput yes
binaryrestart yes
outputEnergies 1000
restartfreq 1000

run 10000000

#########################################################

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