[gmx-users] meaning of results of g_hbond -ac

[Wu Chaofu]

Dear gmxers,
By running the command g_hbond -ac, a resulting .xvg file is generated,
which is attached below. In that file, there are five columns. I guess
that, the first column is time, the second the HB autocorrelation function.
But what are the other columns denoted by s1, s2, s3? Thanks a lot for any
reply.
Yours sincerely,
Chaofu Wu

# This file was created Wed Jul 17 09:49:34 2013
# by the following command:
# g_hbond -f iconf.xtc -s conf.tpr -n -ac ihbac2.xvg
#
# g_hbond is part of G R O M A C S:
#
# GROtesk MACabre and Sinister
#
@    title "Hydrogen Bond Autocorrelation"
@    xaxis  label "Time (ps)"
@    yaxis  label "C(t)"
@TYPE xy
@ view 0.15, 0.15, 0.75, 0.85
@ legend on
@ legend box on
@ legend loctype view
@ legend 0.78, 0.8
@ legend length 2
@ s0 legend "Ac\sfin sys\v{}\z{}(t)"
@ s1 legend "Ac(t)"
@ s2 legend "Cc\scontact,hb\v{}\z{}(t)"
@ s3 legend "-dAc\sfs\v{}\z{}/dt"
         0           1           1  -5.79228e-11    0.902311
         1   0.0995577    0.100186    0.134557    0.455234
         2   0.0895326   0.0901676    0.126435  0.00815676
         3   0.0832442   0.0838836    0.123311  0.00541426
         4   0.0787041   0.0793466    0.117936  0.00376486
         5   0.0757145   0.0763591    0.116489  0.00198866
         6   0.0747267   0.0753721    0.112655  0.00177937
         7   0.0721557   0.0728029    0.109565  0.00255146
         8   0.0696238   0.0702727    0.107288  0.00241577
         9   0.0673242   0.0679747    0.106287  0.00157028
        10   0.0664832   0.0671343    0.104746   0.0014926
        11    0.064339   0.0649916    0.101947  0.00148105
        12   0.0635211   0.0641743   0.0991141  0.00131835
        13   0.0617023   0.0623567    0.101322  0.00147757
        14    0.060566   0.0612212   0.0965892  0.000719808
.....................................................................................