QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: Adila on May 20, 2015, 05:13

Title: Building the structure of blue phosphorene using optimization
Post by: Adila on May 20, 2015, 05:13

Dear Sir,

I had followed the tutorial "http://quantumwise.com/publications/tutorials/item/516-how-to-create-a-crystal-structure-with-the-crystal-builder" to build the structure of black phosphorene.

From my understanding, to build the structure of blue phosphorene, I need to optimize the structure of black phosphorene.

Hence, I followed this tutorial "http://quantumwise.com/publications/tutorials/item/512-opening-a-band-gap-in-silicene-and-bilayer-graphene-with-an-electric-field" for the optimization, using the parameters from these articles "http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.112.176802" and "http://scitation.aip.org/content/aip/journal/jap/116/7/10.1063/1.4893589".
 
However, I'm still having problem to get the structure of blue phosphorene. Do you have any idea on how to build the blue phosphorene?

Attached are the structures of blue phosphorene that I obtained after the optimization step, which are clearly wrong.

Title: Re: Building the structure of blue phosphorene using optimization
Post by: Jess Wellendorff on May 20, 2015, 13:15

So the atomic structure of blue phosporene is really like a graphene sheet, except that all atoms are phosphor and every second atom is displaced down as compared to the others. However, this is not the most stable allotrope of solid phosphor, so it is most likely meta-stable. Not all initial guesses for the structure will therefore relax to blue phosphorene when using Geometry Optimization.

One quick way to set up this structure is using the Nanosheet plugin in the Builder: Use (m,n) = (1,1) for the C-vector alignment with the unit cell. This produces a graphene sheet (4 atoms in the rectangular unit cell). Next, change all atoms to P, and use Coordinate Tools -> Translate to displace 2 of the atoms a few Angstroms along the x axis. Lastly, center the atoms in the unit cell, and change the unit cell lattice parameters to (A, B, C) = (10, 6, 3) Å while keeping the fractional coordinates of the atoms constant.

I found that relaxing the system produced by the above procedure leads to blue phosporene with P-P distances of 2.27 Å (see attached script).

- Jess