QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: PR on February 18, 2015, 11:08

Title: Polarization result mismatch in BaTiO3 crystal
Post by: PR on February 18, 2015, 11:08
Hi all,
I am trying to reproduce the results of polarization in BaTiO3 using ATK 2014.2 version, as given in your tutorial at link :
http://quantumwise.com/documents/tutorials/latest/Polarization/index.html/chap.batio3.html#sect1.batio3.structure
I am following all the steps as mentioned in tutorial, but getting different values from tutorial result.
Attaching the snapshots of calculation and results which I am getting.
Can somebody tell me the reason for this discrepancy?
What should I do to get the correct results.
Title: Re: Polarization result mismatch in BaTiO3 crystal
Post by: Umberto Martinez on February 18, 2015, 21:32
Your results look fine, the numbers are essentially the same.
Title: Re: Polarization result mismatch in BaTiO3 crystal
Post by: PR on February 19, 2015, 07:55
Thanks for the reply.
The numbers are not same. If you see carefully, I am getting the order of -15 instead of -16 in Total Fractional Polarization second row. 
Can you please explain the reason (if possible). And how can I get the same results as in tutorial.

Thanks
Title: Re: Polarization result mismatch in BaTiO3 crystal
Post by: Umberto Martinez on February 19, 2015, 10:50
Yes I see that, and I read 0.000 and 0.000.
the last value of 0.2846 C/m^2 is more interesting.
Title: Re: Polarization result mismatch in BaTiO3 crystal
Post by: PR on February 19, 2015, 11:20
I didn't get you. I think you are talking about Ionic fractional polarization, while my question is about Total fractional polarization.
Again attaching the snapshot. Please see the highlighted part only and compare the powers (-15 and -16) with your tutorial.
 
Title: Re: Polarization result mismatch in BaTiO3 crystal
Post by: Anders Blom on February 19, 2015, 12:39
Pt is 0 in x and y, but not in z.

1e-15 or 1e-16 is zero, the difference to the tutorial is just numerical noise.