[gmx-users] how to calculate the viscosity of the bulk

[Yanmei Song]

Hi, Justin:

I saw in the manual that by g_energy -vis the viscosity of the system
can be calculated. But when I perform the command i got this:

@    title "Bulk Viscosity"
@    xaxis  label "Time (ps)"
@    yaxis  label "\8h\4 (cp)"
@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 "Shear"
@ s1 legend "Bulk"
   19.9601     182.954     131.299
   39.9202     195.973     134.808
   59.8802     209.345     130.015
   79.8403     220.959     129.291
   99.8004     227.397     133.514
    119.76     224.858     128.183
   139.721      234.26     124.201
   159.681     239.432     112.779
   179.641     233.247     90.5362
   199.601     235.796     83.3315
   219.561     232.205     80.3525
   239.521      219.87      78.862
   259.481     216.261     84.9063
   279.441     221.782     81.2453
   299.401     221.704     76.6335
   319.361     212.225     83.4834
   339.321     209.746     95.7125
   359.281     208.776     100.049
   379.242     209.623     101.467
   399.202      204.93     111.357
   419.162     196.223     117.499
   439.122     198.347     121.818
   459.082      200.15     118.537
   479.042     203.718     105.464
   499.002     209.584     98.6823
   518.962     215.025     101.854
   538.922     226.533     102.949
   558.882     229.609     97.6396
   578.842     228.081     96.0029
   598.802     237.529     95.4091
   618.762     245.169     95.4332
   638.723     253.263     97.1168
   658.683     251.794     86.5936
   678.643     242.619      72.306
   698.603     235.621     63.5751
   718.563     230.813     67.5429
   738.523     236.095     78.8719
   758.483     240.001     84.0771
   778.443     246.356     88.0818
   798.403      256.28     91.1965
   818.363     267.644      95.403
   838.323     272.758      102.16
   858.283     278.369     101.837
   878.243     281.149      98.535
   898.204     268.186     93.7993
   918.164     254.442     81.3065
   938.124     239.547     78.0454
   958.084     221.896     87.4938
   978.044     213.811     103.699
   998.004     207.287     113.678


My question is what the value should be for the viscosity of the
fluid. Should I average all the values of third column to get the
value. Does the value have a unit of cp?

Thank you so much in advance!

Yanmei Song
Department of Chemical Engineering
ASU