Quantum Correction at Low Temperature

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1

Hi ,

Is there a way to incorporate quantum corrections in LAMMPS ?

Thanks !

2

Hi ,
Is there a way to incorporate quantum corrections in LAMMPS ?

what quantum corrections to what?

axel.

3

Hi, I’m assuming you were referring to the quantum correction of temperature in classic MD. I would say that depends on the materials you are simulating and could be easily done with post-processing. There are some papers talking about this. Let me know if you need these papers.

Cheers,

A. J. Cao

4

Hi Albert,

Yes, I was referring to quantum corrections to the temperature in classical-MD. Is there a straightforward way to implement it ? I also think one can calculate the free energies and apply quantum corrections to them using the Wigner-Kirk-wood expansion. But I guess those would be fairly tedious.

I am simulating graphene.

It’d be great if you could give me the relevant references.

Thanks !!!

5

Hi Gauri,

The quantum correction to the temperature in classical MD is usually done using Debye model. This will need a Debye temperature. However, graphene is a special case because 1) graphene is 2D (different DOS with 3D), 2) there are three modes: longitude, transverse, and Z modes (They have different group velocities), 3) not all branchs of its phonon dispersion can be treated as linear (one should be parabolic). A linear phonon dispersion and one constant group velocity is a default assumption in Debye model. Therefore, you need to follow the Debye model procedures to produce the specific equation for quantum T-correction of graphene. In the procedure, you can choose not to include the “zero point” energy. These can all be done in post-processing and it is the best way. Actually, the correction is large and makes a huge difference.

Cheers,

6

Gauri: Check out this paper: J. R. Lukes and H. Zhong, Journal of Heat Transfer 129 (6), 705-716 (2007). Although, it is still under debate what debye temperature of CNT/graphene is, you could follow the idea of this paper to get the quantum correction done as you wish.

Best,

Ajing

7

Gauri,

Please check out the paper we recently published: Jingchao Zhang, Xiaopeng Huang, Yanan Yue, Jianmei Wang, Xinwei Wang, 2011, “Dynamic response of graphene to thermal impulse,” Physical Review B, Vol. 84, 235416.

It has the details to do quantum correction on the temperature of graphene, it is different with the common quantum correction because graphene is 2D and has 3 modes just like I said in previous post. Please let me know if you have any question.

Best,