Dear Attia Batool,

If you have a "unit cell (U)" it is easy.  Just replicate it to make a "supercell (S)" and then replace an atomic position with a dopant.  As the number of atoms increases the computation time also increases which in turn decreases the speed. The processing time will be large particularly at k-Point sampling.  Equally, the K Points graph may disappoint as usual.

Few research papers/ articles are mentioned for your reference.

01. http://www.electrochemsci.org/papers/vol7/7043362.pdf

02. https://pubs.rsc.org/en/content/articlehtml/2014/cp/c4cp01000k

03. https://www.hindawi.com/journals/jnm/2012/484692/

04. Article First-principles simulation and experimental evidence for im...

05. http://archives.njit.edu/vol01/etd/2010s/2015/njit-etd2015-065/njit-etd2015-065.pdf

I hope I have answered your question.

With Best Wishes,

Samir G. Pandya

Dear

In a material studio, first draw unit cell and select your pure atoms. Click composition, then adding doped atoms with different compositions. If you convert unit cell to supercell, composition time also increase which in turn decrease the spreed.

Two research paper was attached.

I hope i have answered your questions.

@@ Nurul Islam thanks

Samir G. Pandya thank you sir

Find symmetry and impose is very important, especiall if you are looking for ferromagnetic ordering. You can contact me if you need further assistance.

Regards

I want to work on some selenide materials

What is your crystal system? How about the dopant? There are two types of modeling that can be simulated in CASTEP code, namely coherent potential approximation CPA and virtual crystal approximation VCA. Using the later one, you need large supercell to study the effect of low doping concentration.

Dear,

I am also agree Mohammed M. Obeid . First you select dopant atom, then you click your structure. Example you doped Mn with Co, Select Mn then you added Co with different concentration. ( This is the virtual crystal approximation VCA method).

But i have a question Mohammed M. Obeid sir, how i can simulated optical properties, in VCA OR CPA methods ?

Thanks all

Hello Islam,

Please do not forget to use "Find and Impose symmetry" (along with "options" tab) before you are running a geometry optimization of the doped crystal system. After a successful optimization, optical properties can be achieved after a single point energy run utilizing norm-conserve pseudopotentials with higher energy cutoff and fine k-point mesh because CASTEP code unable to permit non-local correlation energy effects to the optical properties using ultrasoft pseudopotential.

Please check out my recent published paper titled " First-principle analysis of the structural, mechanical, optical and electronic properties of wollastonite monoclinic polymorph"

i am using CASTEP just selecting cif file and run it in software, for example i want to see some DOS and PDOS but I cant get any PDOS and electron density the Import function of electron density and PDOS are in active, I tried too much but I cant get

PDOS

thank you..

Dear Mohammed M. Obeid, Attia Batool and Ali Benghia sir,

How to calculate optical properties in doping compound?

The title compound name TiO2, with doped Al.

Mohammed M. Obeid Samir G. Pandya

What will you tell about Avagrado software?

Dear Nurul Islam

to my knowledge we can't calculate first order properties ( phonon, optic..) and population using virtual crystal approximation by CASTEP

Hello Nurul Islam ,

TiO2 exist in many forms, namely Rutile, Anatase and brookite. Which form of TiO2 will you work on? What is your Al doping concentration ? Simply, create a supercell, substitute one or more Ti with Al (be careful about the oxidation state of the both), do geometry optimization with specific Cutoff energy and k-point mesh, check "optimize cell" box... run. Or, you can do geometry optimization without doping, and then do substitution and geometry optimization for the doped cell to see the effect of the dopant on the unit cell. Before running an optimization, check the optical properties box "properties tab" to get the absorption, refelectivity and much more. Read some literature before doing this work because it is really hard and time consuming.

Hello Majibul Babu I am not using Avogadro .

There are some tutorials in (help) in the CASTEP, it is useful for your work