[gmx-users] number of degrees of freedom

[Carmen Domene]

Dear all,

I am running a simulation which has:

; Compound        #mols
PROTEIN              4
POPC               242
SOL               7938
CL                  15
K                    3

After running grompp, I get the following output:

Number of degrees of freedom in T-Coupling group Protein is 7739.71
Number of degrees of freedom in T-Coupling group POPC is 25409.06
Number of degrees of freedom in T-Coupling group SOL is 47626.23
Number of degrees of freedom in T-Coupling group Cl is 45.00
Number of degrees of freedom in T-Coupling group K is 9.00

I was wondering why I do not get integer numbers for the protein, the
lipid and the water molecules.
In the case of water molecules, I should get 47628 instead of 47626.23 for
example.

I need to know the number of degrees of freedom because I would like to
calculate the temperature for each of the species of this system (that
is the temperature of the Protein, the temperature of the K etc.) when I
couple in the way:

; Groups to couple separately =
tc-grps                  = PROTEIN_K POPC SOL_CL

with

Number of degrees of freedom in T-Coupling group PROTEIN_K is 7748.71
Number of degrees of freedom in T-Coupling group POPC is 25409.06
Number of degrees of freedom in T-Coupling group SOL_Cl is 47671.23

Thanks, Carmen