[SIESTA-L] What is K energy??

[Gregorio García Moreno]

Hi all
My question is not directly related with SIESTA, but I am desperate, I 
do not know where Can I look for the answer.
Who knows which is the equivalency for energy in K units?
I have found a paper (in which SIESTA is used) wherein the units of 
energy in torsional barriers as expresed as Energy (K) relative to minimum.
What is K energy?
I need some help

Thanks in advance