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prisms-center / CASMcode

First-principles statistical mechanical software for the study of multi-component crystalline solids
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Errors in calculating heating capacity from MC simulation #232

Open ghost opened 2 years ago

ghost commented 2 years ago

Dear developer,

Thank you for developing the code and it is very inspiring for our research in alloy materials.

I tried to run mc calculations to simulate the order-disorder transition in alloy materials. The output heat capacity shows the following pattern:

image

However, when I looked into formation energy, it seems that the formation energy changes linearly vs T (the overall slope is not changing)after a sudden rise at ~ 1000K. Also, it seems that structures are fully disordered when T is higher than 1000K. image

Is this inconsistency originates from numerical errors when casm calculate heat capacity ? It seems that the small oscillations do matter in calculating heat capacity. Do you know how to solve this problem ? Or does this phenomenon has any physical meaning ?

Thanks.

bpuchala commented 2 years ago

This looks like there is essentially no disorder below 1000 K, and some disorder above, though it's not clear if it is fully disordered yet or not without knowing more about the system..