Questions tagged [harmonic-approximation]

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5
votes
1answer
110 views

Supercell model for a disordered system in phonon calculations using the harmonic approximation

I studied a disordered state (FCC solid solution) and used a special quasirandom structure supercell with 32 atoms to represent the system. After relaxing it thoroughly with ...
14
votes
2answers
966 views

What does it mean to say a material is 'anharmonic'?

I understand that a harmonic picture of the potential in a material isn't enough to study lattice dynamics thoroughly. The quasi-harmonic approximation is a good workaround and helps incorporate ...
16
votes
2answers
586 views

On the nature of zero-point energy (ZPE)

The harmonic approximation gives a non-zero kinetic energy at 0 K for which Heisenberg's uncertainty principle is used as an explanation. A particle at 0 K couldn't be stationary because that would ...