QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: Dipankar Saha on October 29, 2015, 16:56

Title: The actual thickness / Or, the value of the primitive vector "C"
Post by: Dipankar Saha on October 29, 2015, 16:56
Hello,
When you find the volume...say for the hex. lattice of any  2D material ; how do you measure 'c' ?? Is it the actual thickness of the 2D sheet....or, the primitive vector "C" (which includes the vacuum region also)?

Regards_
Dipankar
Title: Re: The actual thickness / Or, the value of the primitive vector "C"
Post by: Anders Blom on October 29, 2015, 17:53
Neither - you don't talk about the volume of a 2D sheet.
Title: Re: The actual thickness / Or, the value of the primitive vector "C"
Post by: Dipankar Saha on October 29, 2015, 19:49
??!!!! :o  / Then how do you write something like....ne= 0.165 /Ang-3 ?? / I thought, you calculate volume using ((root_under 3) / 2). (a^2).(c)   [for hexagonal primitive lattice....]

Title: Re: The actual thickness / Or, the value of the primitive vector "C"
Post by: Anders Blom on October 30, 2015, 03:38
For 2D systems you normally talk about doping densities in terms of sheet density, not volume density.
Title: Re: The actual thickness / Or, the value of the primitive vector "C"
Post by: Dipankar Saha on October 30, 2015, 06:46
That is quite obvious ....!!!  :)  In the end, I have to look for something  like sheet conc.  ( /cm^2) or so.....

Title: Re: The actual thickness / Or, the value of the primitive vector "C"
Post by: Dipankar Saha on October 30, 2015, 06:52
But, if I need to deal with the DOS (as obtained in ATK, for any 2D material ) to reach there....then, how  should I treat the dimensional aspect....... (with the notion of the per unit volume concept, as applicable for the conventional 3D materials)
Title: Re: The actual thickness / Or, the value of the primitive vector "C"
Post by: Anders Blom on October 31, 2015, 06:39
The electron cloud is not constrained to the plane, but "lives" in the entire 3D cell, of course with vanishing density towards the edge of the cell. So the electron density, which is closely related to the DOS, is always a true 3D quantity.