QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: quantumtoday on December 13, 2017, 00:50

Title: Build Hexagonal Closest Packed structure
Post by: quantumtoday on December 13, 2017, 00:50

Hi all,

I want to build a HCP structure 6 atoms/cell from the primitive cell 2 atoms using the VNL builder. How can I do it? Please advise.

Thank you.

Title: Re: Build Hexagonal Closest Packed structure
Post by: Petr Khomyakov on December 13, 2017, 09:39

You may either import this kind of structure by choosing any crystalline material with this lattice type from the Database in the Builder and then modify it according to your specific needs, or make use of the Crystal Builder, see https://docs.quantumwise.com/tutorials/crystal_builder/crystal_builder.html.

Title: Re: Build Hexagonal Closest Packed structure
Post by: quantumtoday on December 13, 2017, 10:28

Thank you for the reply.
I already have a cif file of the primitive cell of 2 atoms (attached, please remove ".txt" in the file name). To build a HCP structure contains 6 atoms/cell, in the supercell of the builder, how do I change values for A', B', C'?

Title: Re: Build Hexagonal Closest Packed structure
Post by: Petr Khomyakov on December 13, 2017, 10:51

There are several options for building a supercell structure with 6 atoms. For example, you may use the Repeat plugin in the Bulk Tools in the Builder to extend the structure along the C-direction, by setting C to 3. If needed, the lattice parameters can be modified in Lattice parameters in the Bulk Tools.

I note that there exist many useful plugins in the Builder, see https://docs.quantumwise.com/tutorials/builder_manual/builder_plugins/builder_plugins.html.

Title: Re: Build Hexagonal Closest Packed structure
Post by: quantumtoday on December 13, 2017, 11:41

The repeating option can not help me to create a structure as I desire.

I would like to see a HCP 6 atoms eventually like this:
https://cdn.miniphysics.com/wp-content/uploads/2010/12/HCP.gif (https://cdn.miniphysics.com/wp-content/uploads/2010/12/HCP.gif)
Do you have any other idea?

Thank you.

Title: Re: Build Hexagonal Closest Packed structure
Post by: Ulrik G. Vej-Hansen on December 14, 2017, 13:44

Looks like you are looking for this:

In the Builder, go to Graphics -> Properties and check "Display equivalent atoms"

This will show atoms at the edge of the unit cell, which are actually belonging to neighboring cells, like the classic textbook-figure you linked to.

Title: Re: Build Hexagonal Closest Packed structure
Post by: quantumtoday on December 14, 2017, 22:55

Hi Ulrik,

Thank you for the useful suggestion. Indeed we see neighbor cells by choosing repetition in Graphic/properties/cells.
 
However, I would like to know if we could convert or build a conventional cell with 6 atoms/cell (as the link bellows) from a primitive cell of 2 atoms?
http://www.ques10.com/p/9196/draw-the-unit-cell-of-hcp-what-is-the-coordinati-1/ (http://www.ques10.com/p/9196/draw-the-unit-cell-of-hcp-what-is-the-coordinati-1/)

Title: Re: Build Hexagonal Closest Packed structure
Post by: Petr Khomyakov on December 15, 2017, 11:50

The unit cell  in the cif file you have enclosed is conventional, which is also primitive in this case, see Computational Materials Science 49 (2010) 299–312. Building a unit cell with 6 atoms means that this cell is built of 3 primitive/conventional cells, and you may build such as unit cell by repeating the primitive/conventional cell in the direction(s) of your interests. 

I note that the unit cell structure shown in the link consists of 12 atoms, i.e., 6 unit primitive/conventional cells. This is also mentioned in the description to the picture.

Title: Re: Build Hexagonal Closest Packed structure
Post by: quantumtoday on December 15, 2017, 22:43

Hi Petr,

Thank you for the new reply and the useful paper.

I think more about my question/problem.