Pierre de Buyl writes:
> The problem is that, when we are pushing the boundaries of science
[1], we find
> ourselves in situations where we cannot convert everything (semi-open
systems,
> subsystems, etc.).
>
> I am in favor of not having 'volume' mandatory. And neither 'density'.
+1
I have situations (simulations of proteins in gas phase) where my
system has an energy and a temperature, but neither volume nor density
(nor pressure). Whether or not one can use thermodynamics on such
systems is hotly debated (the keyword to look for is "thermodynamics
of small systems"). But I don't think a file format should impose a
particular point of view in this debate.
Konrad.