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I'm doing molecular dynamics of $N$ bodies interacting through Lennard-Jones potential. I'm studying the hysteresis phenomena in the phase transition solid-liquid and liquid-solid. Which parameters can I use for determine the temperature at which the phase transition occurs? I'm using some parameters, as potential energy, kinetic energy and pressure, to determine the transition from solid to liquid. They show a strong change a value at melting point. However in the opposite transition this parameters are not a good choice, their change it is smaller that their fluctuations.

Someone knows some different parameters and how to implement them?

Thanks

Matteo

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You can use fluctuations of the energy, or the energy derivative.

The energy as function of temperature shows an inflexion point at the transition temperature, so you would expect the energy derivative to have a maximum at this temperature. But as the energy derivative is not really easy to compute, you may use the fluctuations (as the standard deviation) which is proportional to the energy derivative. This is a nice feature of the equilibrium distribution of the energy.

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  • $\begingroup$ The heat capacity is one of the observables that is typically used to detect phase transitions. It can be computed following the expression given in en.wikipedia.org/wiki/… as you suggest. $\endgroup$
    – Juan M. Bello-Rivas
    Jan 24, 2015 at 21:18

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