Interface reaction estimation

Dear all,
I was trying to analyze the possible reaction pathways between LiCoO2 and Li6PS5Cl and found a decomposition reaction like Li6PS5Cl=Li3PS4+Li2S+LiCl with a reaction energy of -0.086 eV/atom. I tried to get the total energies per atom value using Li6PS5Cl (mp-985592), Li3PS4 (mp-985583), Li2S (mp-1153), LiCl (mp-1185319) as -4.1110 eV/atom, -4.3976 eV/atom, -3.9875 eV/atom, -3.7087 eV/atom respectively which produce the reaction energy as -0.614 eV/atom. The value in MP is -0.86 eV/atom. Please help me to understand.

Hi @Tanmoy_Paul, try this with energies per formula unit and then normalize by atom at the end:

Li6PS5Cl (mp-9865592): -56.5723 eV
Li3PS4 (mp-985583): -148.5841 eV ÷ 4 atoms/f.u. = -37.1460 eV
Li2S (mp-1153): -12.4656 eV
LiCl (mp-1185319): -16.026 eV ÷ 2 atoms/f.u. = -8.0313 eV

dE = (-37.1460 + -12.4656 + -8.0313) - (-56.5723) = -1.0706 eV / mol reaction

dE_per_atom = -1.0523 eV/mol ÷ 13 atoms/mol = -0.08235 eV/atom.

I am using the newest MP database through mp_api, so my answer is slightly different but should be correct.

Matt

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Dear sir @mattmcdermott

Thank for detail instruction,
When I calcualate for Li6PS5Cl (mp-9865592) at 0K, I got the interface chemical energy is -0.08235 eV/atom.
However, I want to calculate the interface chemical energy for Li6PS5Cl=Li3PS4+Li2S+LiCl at 373K,
So I am looking forward to have your guide for calculation,
Thank you so much for helping!

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