Gemanene using Cif

[danial]

Hi Dear ATK Users,

first of all I Should appreciate Dr.Blom et al,

I have some problem to create Germanene via Cif Tutorial..I  don't know exactly the germanene space group and WyCkoff Position, I follow  this article:

Journal of Solid State Chemistry, Volume 180, Issue 5, May 2007, Pages 1575–1581,
Synthesis, structure and electronic structure of a new polymorph of CaGe2
  Paul H. Tobash,    Svilen Bobev
http://www.sciencedirect.com/science/article/pii/S0022459607001004

but my result is not acceptable!

I'm waiting for you Tips.

yours - Danial

[Anders Blom]

I don't quite understand the question. The article is about CaGe2, but you ask about germanene...? Also, in the article you have all Wyckoff positions and space group listed for CaGe2, so presumably you can build that structure. Excluding the Ca atoms (and keeping only a single layer) probably yields germanene. Otherwise, you can also look in the literature for silicene, and just adjust the lattice constant. You will anyway need to optimize the atom positions so you could just start with the buckling in silicene.

Otherwise, please be more specific in your question - what precisely you tried (screenshots, script) and what you obtained, and why this is not satisfactory.

[danial]

Thanks So much for your kind response,

I've tried two following ways to create Germanane:

1- in fact my purpose is making Germanane and Silicane in ATK and then calculate Band Structure and so on.   
for the first step built it via create the  new crystal structure and used beta-CaGe2, then remove Ca atoms, passivated with H and finally geometry optimization. but the results have not been as I supposed.(I  also will attach my results.)

# Set up lattice
lattice = Hexagonal(3.9872*Angstrom, 30.583*Angstrom)

# Define elements
elements = [Germanium, Germanium, Hydrogen, Hydrogen]

# Define coordinates
fractional_coordinates = [[ 0.66666667,  0.33333333,  0.51798333],
                          [ 0.33333333,  0.66666667,  0.48201667],
                          [ 0.60134218,  0.28773871,  0.56743569],
                          [ 0.28773871,  0.60134218,  0.43256431]]

# Set up configuration
bulk_configuration = BulkConfiguration(
    bravais_lattice=lattice,
    elements=elements,
    fractional_coordinates=fractional_coordinates
    )

2- due to my purpose,  I tried to create Germanane and Silicane via Cif, but again have some problem.

data_global
_chemical_name 'Germanane - chair'
_cell_length_a ?
_cell_length_b ?
_cell_length_c ?
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_symmetry_space_group_name_H-M '?'
loop_
_atom_site_label
_atom_site_symmetry_multiplicity
_atom_site_Wyckoff_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
Ge   ??  ??
H    ?? ??

-Is there any article to have these information about Germanane and Silicane?

please help me to find a propel way.

yours- Danial

[Umberto Martinez]

you can have a look to this paper where ATK has been used.
http://dx.doi.org/10.1166/jctn.2014.3428
Also, search through the scientific literature for more references.

Please, attach your cif file so that we can properly read it and use the insert code method to copy and paste python code.

[danial]

Thanks a lot dear Dr.Blom and Mr.Martinez

I will try to create  Germanene and Silicene with great ATK, then I will attach my  codes and results for other users.

thanks so much
Yours - Danial