Dear Hamid,

if you expect an answer to your problem, you must give some details about your liquid for the determination of boiling point. You know that the Lindemann model describes melting in terms of the solid alone. The melting transition will involve solid and liquid phases. Your question is too vague for a correct answer at this time. Please send more details. Thank you in advance

JRG

First of all, the boiling point depends on the pressure.

Second, in a liquid molecules can move to arbitrary distances. It does not make sense to evaluate a Lindemann index in such a case. Or do you want to calculate an intramolecular Lindemann index? This can be done, but would reflect the strength of chemical bonds only and not the boiling point.

Dear Dr. alavi

Thanks for your answer.

@Saman: … a good clarification! But some caution is necessary: For supercritical conditions, one can move from gas- to liquid-like densities (and probably register rather different Lindemann indices) without crossing the vapour–liquid phase boundary. Here the interpretation of the indices as phase indicators would be misleading.

Moreover, the original question was whether we can determine a boiling point with these indices. A boiling point is an equilibrium state. It may be possible to classify a state by means of its Lindemann index as liquid-like or gas-like. But this will not tell you whether this state is a *saturated* liquid or gas. You can determine the phase boundary by performing a series of simulations at different pressures. But then you do not really need the Lindemann index; the density is sufficient.