Messages

1

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

« on: June 5, 2011, 08:09 »

2008.10 VNL

2

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 ...

3

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.

4

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

« on: November 20, 2010, 08:40 »

...
Fermi energy
-1.80426204477 eV

then the HOMO energy is a bit smaller one than -1.80426204477 eV?
and the LUMO energy is a bit bigger one than -1.80426204477 eV?  without comparing them with 0ev???

Just from the results shown by you, the answer is yes.

well, thak you very much.

5

General Questions and Answers / Re: workfunction new ATK

« on: November 19, 2010, 04:51 »

thanks I get 4.29 eV for AL (100) and  4.36 eV for Ag(100)  however i didn't adjust the confnement, maybe that will help the accuracy.

hi buddy,your photo is cool!

6

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

« on: November 19, 2010, 04:47 »

Of course, the Fermi level for the molecular energy levels of up-spin and down-spin are same. Usually, the positions of HOMO and LUMO are determined by the  corresponding electron occupations, rather than the sign of energy values (i.e., negative or positive). Only the energy zero is set as the Fermi level, you can find out the positions of HOMO and LUMO by the sign of  their respective values.  The first eigenvalue of molecular orbitals below the Fermi level corresponds to the HOMO, and the first eigenvalue of molecular orbital above the Fermi level corresponds to the LUMO.

but after i calculated the Fermi energy ,it shows 
                  ......................................
                  ......................................               
                93.79                  93.80
                94.94                  94.94
                94.95                  94.95
                94.97                  94.98
                94.98                  94.99
                95.25                  95.28
                97.35                  97.36
                98.01                  98.03
Fermi energy
-1.80426204477 eV

then the HOMO energy is a bit smaller one than -1.80426204477 eV?
and the LUMO energy is a bit bigger one than -1.80426204477 eV?  without comparing them with 0ev???

7

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
.................................

8

General Questions and Answers / Re: How to define the "Equivalent atoms" by hand ?

« on: June 19, 2010, 14:24 »

question2:it is not necessary to make them in a line .only ensure their difference of z coordinates
id_numbers_Left_electrode means what?

9

General Questions and Answers / Re: how to build the silicon nano-wire?

« on: June 9, 2010, 02:56 »

built a carbon nano-wire first,then change the carbon to silicon?
but how to determine the bond length?
i am also interested in this question.

10

General Questions and Answers / Re: How can I set the distance between two different atoms?

« on: June 4, 2010, 05:47 »

the distance between two different atoms must be optimized according to the total energy.
Choose the distance when you get the smallest energy.

11

General Questions and Answers / Re: central region width

« on: June 2, 2010, 08:25 »

The problem may exist in the contacts between the electrode and the central region.
look at the contact between the left electrode and the scattering region,it is different from the right contact between the right electrode and scattering region.
The structure of your supercell may lead to this difference,because the left border and right border of the supercell is not symmetrical 

This is just my view.

12

General Questions and Answers / Re: central region width

« on: June 2, 2010, 04:44 »

could you please attach your script,i want to know what gives rise to this situation too.
Thank you

13

General Questions and Answers / Re: number of electrodes?

« on: June 2, 2010, 04:39 »

you mean the number of screening layers in the central region.
actually,it depends on the results of SCF.you don't have to add more atoms until the result changes little.otherwise,it will take more calculation time.
besides,the number of atoms don't have to be the same if only the structure obeys  the periodicity .
i am a rookie , this is only my  comprehension

14

General Questions and Answers / Re: Required for two probe system

« on: May 31, 2010, 11:10 »

If you want to know more about how ATK performs the calculations, we refer to the standard article Physical Review B 65, 165401 (2002).

i am effusive in gratitude
Thank you for your helpful assistance
well ,that is a great job to understand all of the article,buddy

15

General Questions and Answers / Re: spin

« on: May 31, 2010, 11:02 »

i mean buddy