Formation energy inconsistency

Certainly! Here’s the English translation of your refined question:


Subject: Question on Discrepancy in NbC Formation Energy Calculation Compared to Materials Project

Hello,

When calculating the formation energy of NbC using Materials Project data, I found a significant difference between my result and the value given on the MP website.

Here are the details:

  • The mp-ids and total energies I used are:
    • NbC: mp-910, E(NbC) = –20.2463 eV
    • Nb: mp-75, E(Nb) = –10.1013 eV
    • C: mp-3347313, E(C) = –9.9472 eV

Based on this, I calculated the formation energy per atom as follows:

Ef = [E(NbC) – E(Nb) – E(C)] / 2 = [–20.2463 – (–10.1013 + –9.9472)] / 2 = –0.099 eV/atom

However, the formation energy reported by the Materials Project is –0.536 eV/atom, which is quite different.

Could someone please help me understand the source of this difference? Am I missing some correction, or perhaps using incorrect reference structures or energies?

Thank you very much for your help!

Best wishes,
Yuefeng Zhang

Take a look at this question and make sure you apply the energy corrections described there