QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: jchang on August 28, 2019, 07:02

Title: work function of bulk material
Post by: jchang on August 28, 2019, 07:02

Hi,

I want to know how to calculate the work function of bulk material.
ATK tutorial about calculating work function is for slab structure having vacuum. And it seems that vacuum is required to set a energy reference.
However, in bulk system, since we don't have vacuum, it is hard to set up any reference by setting up boundary condition.
So, can  we calculate work function of bulk material with ATK?

Thanks.
jiwon

Title: Re: work function of bulk material
Post by: mlee on August 28, 2019, 09:08

The work function is the energy required to remove an electron from the Fermi level of a cleaved crystal to the vacuum level. In section III of the reference paper (Phys. Rev. B 96, 195309), QuantumATK recommends to calculate the work function using the surface green's function or slab model.

Title: Re: work function of bulk material
Post by: jchang on August 28, 2019, 09:26

Thanks for the quick response.
Then, for the bulk work function calculation, do I need to set up a thick slab to mimic the bulk and then do the work function calculation?

Title: Re: work function of bulk material
Post by: mlee on August 29, 2019, 11:35

Unfortunately, I don't have an experience in the case of work function for bulk.

Title: Re: work function of bulk material
Post by: jchang on August 30, 2019, 04:23

I see.  Thanks for your response.
Do you mean that quantumATK cannot calculate work function for bulk?

Title: Re: work function of bulk material
Post by: mlee on August 30, 2019, 10:20

QuantumATK can use slab model or surface green's function (one probe) to calculate the work function because work function will depend on the surface facet. If you have a reference paper of the bulk work function, let us know about it.  That would be great.

Title: Re: work function of bulk material
Post by: Anders Blom on September 10, 2019, 20:58

Quote from: jchang on August 28, 2019, 09:26

Thanks for the quick response.
Then, for the bulk work function calculation, do I need to set up a thick slab to mimic the bulk and then do the work function calculation?

The slab approach is one option, the other is using the unique surface Green's function method in QuantumATK. See
https://docs.quantumatk.com/tutorials/work_function_ag_100/work_function_ag_100.html
https://docs.quantumatk.com/tutorials/work_function_tuning/work_function_tuning.html
https://docs.quantumatk.com/tutorials/gf_surface/gf_surface.html