fix heat

Hello all!
If I want to add a specified amount of heat to a group of atoms and subtract the same heat from another group of atoms should the number of atoms in these two groups be the same?
for example if I have

fix 1 hot heat 100 0.1
fix 2 cold heat 100 0.1
should the number of atoms in the groups hot and cold be the same?

**If it is different in the following:

fix 1 all heat 100 0.1 region hot
(which the region hot is almost the same as group hot) please tell me.

I appreciate in advance,

Hello all!
If I want to add a specified amount of heat to a group of atoms and
subtract the same heat from another group of atoms should the number of

please note that fix heat determines a *rate* of how much kinetic
energy is transferred, to make it a specific *amount* it is crucial
that the simulation lasts for a corresponding specific *duration*
(better double and triple check the units, too!!).

atoms in these two groups be the same?

no.

for example if I have
fix 1 hot heat 100 0.1
fix 2 cold heat 100 0.1
should the number of atoms in the groups hot and cold be the same?

no.

**If it is different in the following:
fix 1 all heat 100 0.1 region hot
(which the region hot is almost the same as group hot) please tell me.

i don't understand what you are asking here.

axel.

And not that the fix heat param you specify is for all the atoms in the group.
Thus if you use it twice with the same param (sign flipped), and one group
has 1000 atoms and the other has 100, then the per-atom effect in the
first group will by 10x smaller than in the 2nd group.

Steve