Charge State Calculation for periodic System in CRYSTAL17

R.Zosiamliana

Dear CRYSTAL community,

I am working on charge state calculations using CRYSTAL17 and would like clarification on how to correctly set up a system with a net charge.

I am studying bulk hydride LiBeH3 and intend to simulate it in different charge states (e.g., [LiBeH3]+1 and [LiBeH3]-1 i.e., LiBeH3 compound with net +1 or -1 charge).

Thank you,
R. Zosiamliana
PSRC, Pachhunga University College
Mizoram, India.

aerba

Hi,

To run a calculation with a not neutral unit cell, you must insert the keyword CHARGED at the end of the basis set input block, as in:

Title
[geometry]
END
[basis set]
CHARGED
END
[SCF parameters]
END

Hope this helps,

Aleks

Hi,

If I may, I'll add a few more lines on Alessandro's comment that might be of use (or not...)

Let's say you want to change the charge state of one of the Li atoms in your cell. Assuming that it is atom number XY with atomic number 3, your input might look something like this:

Title
[geometry]
END
[basis set]
...
3 3       -> Li example basis set
0 0 6 2. 1.
 700.0 0.001421
 220.0 0.003973
 70.0 0.01639
 20.0 0.089954
 5.0 0.315646
 1.5 0.494595
0 0 1 1. 1.
 0.5 1.0 
0 2 1 0. 1.
 0.6 1.0 
...
99 0
CHEMOD
1
XY             -> atom number whose charge you change for the initial guess
2.0 2.0 0.0    -> electronic charge of all shells in the basis set, here you alter the initial charge guess 
                  (note that the initial configuration is 2.0 1.0 0.0, so you will end up in the "-1" charge state)
CHARGED
END
[SCF parameters]
END

As usual, supercell size should be converged, localization of the defect confirmed, etc. Good luck with the defect formation energy corrections...one way to go is to use the multipole correction (aka Makov-Payne, see e.g., 2010 J. Phys.: Conf. Ser. 242 012004 or PRB 81, 205214 (2010))...or you can write your own piece of code to interface CRYSTAL's output to for example the scheme of Kumagai and Oba (Phys. Rev. B 89, 195205) !

Hope it helps.

Cheers,
Aleks