How to obtain the magnitude of atomic fluctuations

[Shudong Wang]

Dear all,

I want to calculate the fluctuations of th atoms in my system, like as in paper "J. Phys. Chem. Lett. 2016, 7, 653.659" about he black phosphorene.

How to set input or how to deal with the output to get this  value?

Thanks!

Shudong

[Alexey Akimov]

Hi Shudong,

There is nothing special about it - you'd just need to read the coordinates of the atoms of interest obtained from the MD. This can be done with the out2xyz or out2pdb modules of the Pyxaid1/2. Once you have the coordinates, you can analyze them with a Python script. Perhaps, Run Long has such scripts.

Best,

Alexey

[Shudong Wang]

Dear Alexey,

I have a question about the hot carier cooling process. In general, the large NACs, the samll energy gap and large dephasing time could lead to the fast cooling. For dephasing, the more 

phonon modes interact with electron subsystem(e.g. the more modes appears in the spectral density plot), the fast the phasing time, and thus the more slower the cooling.

However, the phonon-assisted electronic transitions can acelerate the cooling, so the more phonon modes interact with the electrons, the fast the cooling. This process seems incompatible with the above mentioned in the dephasing time. How could we understand these two process?

Thanks!

Shudong

[Alexey Akimov]

Hi Shudong,

It is usually a balance between couplings and dephasing. Yes, strong el-ph coupling leads to larger NACs which could result in faster transitions. On the other hand, it stronger el-ph. interactions can lead to faster dephasing, and hence to potential slow down of dynamics (quantum Zeno effect in the limit). Sometimes NAC wins, sometimes dephasing. 

Best,

Alexey