Dear all,

I am interested in finding the melting temperature of a copper (Cu) island on a titanium nitride (TiN) substrate. I have attached an image of a simulation cell that I am using for this purpose with a Cu island composed of 100 red atoms on a TiN substrate with blue N and yellow Ti atoms.

Reading the paper “Entropy based fingerprint for local crystalline order” and the related LAMMPS documentation, I thought compute entropy/atom command in LAMMPS could be useful to help me find the melting temperature of the very small island in terms of entropy/atom, i.e., the temperature at which the island starts to melt by becoming significantly disordered. However, I have some questions that I really appreciate it if someone could provide me with some hints or answers.

- Is entropy/atom applicable to the case that I am working on at all? If yes, is it necessary that the entropy/atom commend to be computed for only Cu atoms or the whole simulation cell in my case? For example, should I use

compute 1 * all* entropy/atom 0.25 5.5 avg yes 3.5 local yes,

or

compute 1 * Copper* entropy/atom 0.25 5.5 avg yes 3.5 local yes ?

Is there any commend that can modify the neighbor list of this compute such that only Cu atoms are considered in the computation?

- If I understood the paper and the LAMMPS documentation correctly, it may be better to use the following command for my case:

compute 1 group-ID entropy/atom 0.25 5.5 avg yes 3.5 local yes

is it appropriate to use keywords * avg* and

*? What values are suitable to be considered for*

**local yes***,*

**sigma***, and*

**cutoff***? By the way, the potential that I have predicts the following lattice constants at 0K: a_TiN = 4.2146 Å a_Cu = 3.62 Å.*

**cutoff2**- I am interested to investigate temperatures up to 1000K. So, is it necessary to adjust the parameters
,**sigma**, and**cutoff**at different temperatures? If yes, is there any suggestion?**cutoff2**

Many thanks in advance for your time and stay safe,

Reza Namakian.