Topics

1

General Questions and Answers / How to draw the picture of surfaces of constant LDOS at the fermi energy?

« on: June 5, 2011, 08:05 »

How to draw the picture of surfaces of constant LDOS at the fermi energy?

Thank you ...

2

General Questions and Answers / How to calculate the spin filter or spin-polarized current of a two-probe system

« on: June 5, 2011, 07:58 »

How to calculate the spin filter or spin-polarized current of a two-probe system?

When calculating the spin-polarized current, should i have to add an bias?

Thank you very much.

3

General Questions and Answers / ATK2008.10 questions about：molecular energy spectrum

« on: November 18, 2010, 06:44 »

After calculating the molecular energy spectrum with the initial spin has been given to the molecule，in the output result，how can i identify which is the HOMO energy（just the negative value below zero？）and the LUMO energy（the first positive value up zero？ ）of two different spin electrons。
thank you for your attention。

大家算过的给点意见啊，谢谢啦。就是 分子中不同自旋的电子的费米能级也是一样的吗？homo-lumo是用 零值左右的正负值来表示？ 我算出的费米能级是负值，并且上面还有几个负值的能级。应该怎么理解呢？

期待。急用，谢谢大家。

Thank all of you  again
.................................

4

General Questions and Answers / help explaining the physical meaning of these words

« on: May 22, 2010, 16:00 »

SingleZeta

SingleZetaPolarized; SingleZeta plus one basis orbital for the first unoccupied shell

DoubleZeta; two basis orbitals for each valence orbital

DoubleZetaPolarized; DoubleZeta plus one basis orbital for the first unoccupied shell

DoubleZetaDoublePolarized



Can someone explain these words to me ?And tell me their difference.
Thank you.

5

General Questions and Answers / what's the meaning of this error?

« on: May 15, 2010, 02:57 »

Traceback (most recent call last):
  File "opt_CoFe.py", line 99, in ?
    runtime_parameters = runtime_params
NLInternalError: Quasi Newton minimization unable to reach minimum with given force tolerance.


after optimizing the geometry,here comes the error.i don't know what to do .
somebody help me ,thanks very much

6

General Questions and Answers / an extremely weird problem( between the code and VNL)

« on: May 8, 2010, 16:04 »

hi everyone,i found a strange phenomenon minutes ago;
first, a two-probe-configuration in my script ,the coordinates of the atoms in central-region is wrong,but when i drag  it to vnl,the picture is just what i want to get.then i move the mouse to one atom of them,i find that the coordinate of that atom is not coincide with the coordinate of the script.How odd!
the picture is right.

Code

from ATK.TwoProbe import *
# Li chain lattice constant
a =2.05
# Construct the electrode unit cell
unit_cell = [
[3*a, 0.0, 0.0 ],
[0.0, 3*a, 0.0 ],
[0.0, 0.0, 4*a ]
] * Angstrom
# Define the electrode
electrode_Co = PeriodicAtomConfiguration(
super_cell_vectors = unit_cell,
elements = 4*[Cobalt],
fractional_coordinates = [
(0.5, 0.5, float(i)/4.0) for i in range(0,4)]
)
# Setup the two-probe scattering region

# The atoms in the central region
elements =[Cobalt,   Cobalt,   Cobalt,   Carbon,   
                       Carbon,   Carbon,   Carbon,   Carbon,   
                       Hydrogen, Hydrogen, Hydrogen, Hydrogen, 
                       Hydrogen, Iron,     Carbon,   Carbon,   
                       Carbon,   Carbon,   Carbon,   Hydrogen, 
                       Hydrogen, Hydrogen, Hydrogen, Hydrogen, 
                       Cobalt,   Cobalt]
d=5
z=6*a+d

positions = [
[4.35, 4.35, 4*a],
[4.35, 4.35, 5*a],
[4.35,4.35,6*a],
[  4.73919   ,   5.54389999,  z-1.60856],
                          [  4.73877003,   3.16335998,  z-1.60963],
                          [  5.60394   ,   4.3535    ,  z-1.61524],
                          [  3.34037005,   5.08904997,  z-1.61793],
                          [  3.34012007,   3.61865   ,  z-1.61376],
                          [  5.09579002,   6.64246998,  z-1.53029],
                          [  5.09504001,   2.06411991,  z-1.53191],
                          [  2.40435003,   5.76681004,  z-1.54651],
                          [  2.40367006,   2.94073997,  z-1.55516],
                          [  6.75891005,   4.35323   ,  z-1.54403],
                          [  4.35      ,   4.35      ,  z],
                          [  4.73919   ,   5.54389999,  z+1.72744],
                          [  4.73877003,   3.16335998,  z+1.72637],
                          [  5.60394   ,   4.3535    ,  z+1.72076],
                          [  3.34037005,   5.08904997,  z+1.71807],
                          [  3.34012007,   3.61865   ,  z+1.72744],
                          [  5.09579002,   6.64246998,  z+1.80409],
                          [  5.09504001,   2.06411991,  z+1.78949],
                          [  2.40435003,   5.76681004,  z+1.78084],
                          [  2.40367006,   2.94073997,  z+1.79197],
                          [  6.75891005,   4.35323   ,  z+1.80571],
[4.35,4.35,z+d],
[4.35,4.35,z+d+a]

] * Angstrom
# Combine electrode and scattering region
# into a two-probe system
two_probe_conf = TwoProbeConfiguration(
electrodes = (electrode_Co,electrode_Co),
scattering_region_elements = elements,
scattering_region_cartesian_coordinates = positions,
)
# Export the two-probe configuration to a VNL file
vnl_file = VNLFile("CoFeCo.vnl")
vnl_file.addToSample(two_probe_conf, "CoFeCo")

drag it to vnl,and observe its X,Y coordinates.
Can somebody explain it ?Thanks