changing solventDielectric in GBIS

From: Andres Colubri (
Date: Mon Jun 13 2011 - 07:36:41 CDT


I'm simulating a heating cycle using the new GBIS model in NAMD,
starting at T=275 K and ending at T=300K, with increments of 5 degrees.

Since the dielectric of water goes from 88 at 0C to 78 at 28C, the
simulation script should update the solventDielectric parameter
accordingly at each temperature step. So I have the following in
my config file :

# Heating
for {set i $temperature0} {$i <= $temperature1} {incr i 5} {
   set temperaturei $i
   langevinTemp $temperaturei
   langevinPistonTemp $temperaturei
   solventDielectric $dielectric($temperaturei)


set temperature0 275
set temperature1 300


set dielectric(275) 87.31
set dielectric(280) 85.46
set dielectric(285) 83.61
set dielectric(290) 81.76
set dielectric(295) 79.91
set dielectric(300) 78.06

However, I get this error in the first iteration of the loop:

TCL: Setting parameter solventDielectric to 87.31
FATAL ERROR: Setting parameter solventDielectric from script failed!

Any help with this will be greatly appreciated.

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