[gmx-users] Force Constants and Unit Systems

[Lara Bunte]

Hello

I never had contact with such units. Could you please help me and explain me how to transform following units:
 
1.)
kcal / mol --> kJ / (mol * nm^2)

2.)
kcal / (mol * rad^2) --> kJ / (mol * rad^2)

I have additionally some question to that:  Both should be units of a force constant. From Hooke's law F = -kx follows for me, that the unit of a force constant is Newton N over distance m, in S.I. units  kg/sec^2 (mass over time square).

What is the correspondence between above from Hooke's law and that units of force constants in molecular dynamics simulations? 

Thanks for helping me
Greetings
Lara