AKMC or KMC simulations

[ramya]

I would like to perform either AKMC or KMC simulations for determining the bulk diffusion of dopants or impurities on thin film solar cells. I would like to know is it possible to perform such kind of simulations using Quantumwise. If possible, I would like to know how we can do it. Is it possible to get the license for this software.

[Petr Khomyakov]

It is possible to do AKMC simulations for the bulk diffusion of dopants in the VNL-ATK. Please have a look at the following two tutorials:  http://docs.quantumwise.com/tutorials/boron_diffusion_in_si/boron_diffusion_in_si.html and http://docs.quantumwise.com/tutorials/akmc-empirical-sige/akmc-empirical-sige.html.

Regarding the license issue, it is absolutely possible to get it for the VNL-ATK software package, see the relevant information on the licence options, and request the license that suits your needs at http://www.quantumwise.com/products/purchase.

[ramya]

What kind of potentials are employed during AKMC simulations. Is it possible to regular KMC also using Quantumwise.

[Petr Khomyakov]

You may find a list of classical potentials implemented in ATK at http://docs.quantumwise.com/manuals/ATKClassical.html.

In principle, it is possible to do just KMC simulations in ATK, but we do not have a tutorial on that, and have not done any intensive testing for regular KMC. Is there any particular reason why you want to use KMC instead of AKMC, which is " an algorithm for performing Kinetic Monte Carlo (KMC) simulations on-the-fly without having to have a predefined set of states and reaction mechanisms"?

[ramya]

Since, we are already know the paths from NEB, that why we would like to perform KMC simulations.

[zh]

The purposes of NEB and KMC are different. Please refer to wiki for KMC:
https://en.wikipedia.org/wiki/Kinetic_Monte_Carlo

[ramya]

I am  aware of that but we want to see the influence of temperature on barriers.

[Julian Schneider]

The way we calculate barriers in AMKC does not take into account temperature, as in NEB everything is calculated at 0K. Temperature only comes into play when the rate constants are calculated, which we do using the harmonic transition state theory (HTST) formalism in our HTSTEvent analysis object.

If you have a single transition for which you have calculated an NEB, and you want to study the effect of temperature on the forward and reverse rate constants of this transition, you can directly use this HTSTEvent analysis object ( see http://docs.quantumwise.com/manuals/Types/HTSTEvent/HTSTEvent.html#htstevent-c). Once you have calculated and stored this analysis object, we have a LabFloor plugin called HTST Rates which calculates a variety of properties for this transition.

[zh]

I am  aware of that but we want to see the influence of temperature on barriers.

The influence of temperature on barriers could be taken into account by post-processing the calculated vibration frequencies of diffusion particles in  saddle points and end points on the basis of quasi-harmonic approximation.  Please refer to the following paper:
Vacancy migration in hexagonal boron nitride
A. Zobelli, C. P. Ewels, A. Gloter, and G. Seifert
Phys. Rev. B 75, 094104 – Published 8 March 2007