BAR-estimator error of ParseFEP plugin version 1.5 in VMD 1.9.1

From: dbaogen (
Date: Tue May 07 2013 - 00:10:40 CDT

Dear all,

              The ParseFEP 1.5 can not output the value of free energy using BAR-estimator. The fepout files of forward and backward includes 40 windows, respectively. and total 1 ns is run for each window.

               After treating each window of forward and backward, the error occurred to carry out BAR-estimator . The error message is as follow:
divide by zero
 divide by zero
     while executing
 "expr { $deltaA + $::ParseFEP::kT * log ( $length_backward / $length_forward ) } "
     (procedure "::ParseFEP::deltaAtoC" line 2)
     invoked from within
 "::ParseFEP::deltaAtoC $deltaA_0 $len_forward $len_backward "
     (procedure "::ParseFEP::bar_estimate" line 94)
     invoked from within
     (procedure "::ParseFEP::namdparse" line 167)
     invoked from within
     (in namespace inscope "::ParseFEP" script line 22)
     invoked from within
 "::namespace inscope ::ParseFEP {
         ##if {$::ParseFEP::fepbofile != ""} {set ::ParseFEP::sosindex 1 }

         if { [string length $fepofile] < 1 } {
     invoked from within
 ".parseFEP.runbutton invoke"
     ("uplevel" body line 1)
     invoked from within
 "uplevel #0 [list $w invoke]"
     (procedure "tk::ButtonUp" line 22)
     invoked from within
 "tk::ButtonUp .parseFEP.runbutton"
     (command bound to event)

Would you like to give me some help? Thanks in advance.

Duan Baogen

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