#0 center of mass: 29.5741 29.9514 29.7281, radius of gyration: 3010.778

#0 center of mass: 29.5741 29.9514 29.7281, radius of gyration: 3010.778

This looks unrealistic and seems to be off by at least 3 orders of magnitude. 

I used the following script based on AmberTools15

I get a radius of gyrations with mean ~ 1.8 angstrom. See snapshot attached.

For easy reference, the AmberTools15 manual states (p.586)

radgyr | rog

radgyr [name>] [<mask>] [out <filename>] [mass] [nomax] [tensor] 

[<name>] Data set name.
[<mask>] Atoms to calculate radius of gyration for; default all atoms. [out <filename>] Write data to <filename>.

[mass] Mass-weight radius of gyration.
[nomax] Do not calculate maximum radius of gyration.
[tensor] Calculate radius of gyration tensor, output format ’XX YY ZZ XY XZ YZ’. Data Sets Created:

<name> Radius of gyration in Ang.
<name>[Max] Max radius of gyration in Ang.
<name>[Tensor] Radius of gyration tensor; format ’XX YY ZZ XY XZ YZ’.

Calculate the radius of gyration of specified atoms. For example, to calculate only the mass-weighted radius of gyration (not the maximum) of the non-hydrogen atoms of residues 4 to 10 and print the results to “RoG.dat”: