QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: JHON.GAB on January 30, 2012, 13:16

Title: Symmetry points
Post by: JHON.GAB on January 30, 2012, 13:16

how to calculate total no. of k-points used in the calculation as other software like castep shows in their window >:(

Title: Re: Symmetry points
Post by: Anders Blom on January 30, 2012, 15:23

If you do

Code: python

kpts = MonkhorstPackGrid(3,3,3)
print kpts.kpoints()
print("Number of k-points: %s" % len(kpts.kpoints()))

you will see the k-points used in a time-reversal symmetrized 3x3x3 Monkhorst-Pack grid.

Code: python

kpts = MonkhorstPackGrid(3,3,3,force_timereversal=False)
print kpts.kpoints()
print("Number of k-points: %s" % len(kpts.kpoints()))

gives it without the symmetrization.

Currently ATK does not reduce the k-point sampling by crystal symmetry, but this will come in the future. (Transmission spectrum and DOS calculations are symmetry optimized.)

Title: Re: Symmetry points
Post by: JHON.GAB on January 31, 2012, 09:30

i have CNT (15,0) optimized, in 3-d properties of this figure it is shown under geometry box radius and length, is it a length and radius of CNT if it is then it is wrong according conventional formulae of diameter,,,, please guide  ,,,,,,,,,,,,,,,?

Title: Re: Symmetry points
Post by: Anders Blom on January 31, 2012, 10:23

In the 3D properties? That's just the view settings, how thick you want the radius of the cylinders that form the bonds to be etc.

Title: Re: Symmetry points
Post by: POP on January 31, 2012, 11:31

Thanks..... :)

Title: Re: Symmetry points
Post by: JHON.GAB on February 1, 2012, 07:43

what is unit cell padding in custom menu and why it is only in xy direction ,i searched in manual but not cleared? plz help me

Title: Re: Symmetry points
Post by: Anders Blom on February 1, 2012, 07:44

It specifies how much vacuum you want around the tube. And then it's obvious why it's only in xy :)

Title: Re: Symmetry points
Post by: JHON.GAB on February 4, 2012, 07:12

Dear sir,
      I have GaN naotube without optimization there is bond between both Ga-Ga and Ga-N but after optimization there is bond between Ga-N only,,,,what's the meaning of this?  plz help me.......... >:(

Title: Re: Symmetry points
Post by: JHON.GAB on February 4, 2012, 07:16

here are the snap shots....

Title: Re: Symmetry points
Post by: Anders Blom on February 4, 2012, 19:35

The bonds shown in the 3D window are graphical only, they are not used in the calculation at all. They are drawn based on criteria concluded from the usual covalent radii of the two atoms forming the bond, and to which extent these radii overlap. I am inclined to think that it's rather your initial structure which has too short bonds, and the optimized structure is proper, since you would not imagine having real Ga-Ga bonds in this kind of structure.

Title: Re: Symmetry points
Post by: JHON.GAB on February 6, 2012, 07:08

Thank's :)