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Topics - jerry

Pages: 1 [2] 3
16
General Questions and Answers / GNR calculation
« on: December 4, 2011, 12:10 »
Dear,
 
    Recently, i have done some calculation for GNRs with armchair and zigzag shaped edges. The DFT results show that the aGNR is semiconducting or metallic which depends on its width, while zGNR is metallic. The results correspond to some other calculations quite well. However, some calculation show that both aGNR and zGNR are semiconducting (PRL 97, 216803 (2006)). Can someone help me explain this discrepancy?
 
Thanks a lot!
                                                                                                Jerry

17
General Questions and Answers / How to calculate the magnetic moment for a molecule or a bulk?
« on: November 29, 2011, 01:56 »
Dear,

    I want to calculate the magnetic moment for a molecular structure and the unit cell of a bulk structure using ATK? Can you give me some references on this ?

    Best regards!

    Jerry

18
General Questions and Answers / How to export the structures in a xyz form
« on: November 15, 2011, 14:58 »
Dear,

    I want to export the structures in ATK in a xyz form so that the structures can be processed through other softpackages, such as VASP,  LAMMPS and Materials Studio.

    Thanks a lot! :D
                                         
    Jerry

19
General Questions and Answers / Install problem in ATK 11.8.0
« on: November 12, 2011, 06:49 »
Dear,
   
     I installed the ATK11.8.0, when i run this version, something goes wrong. Set minimum Size: (Qlabel) negative Sizes (-1, -1) are not possible. But ATK can still run.

20
General Questions and Answers / DFT calculations for two probe systems
« on: November 5, 2011, 03:58 »
Dear,
    Recently, i have read some papers that attribute the discrepancy between calculated conductance and measured one to the underestimation of the HOMO-LUMO gap of DFT methods. Usually, this discrepancy is orders of magnitude. I want to know whether this kind of argument is reasonale, as the main effect of the underestimation of HOMO-LUMO gap is the decrease of the conductance gap.

21
General Questions and Answers / Mulliken population
« on: November 2, 2011, 08:58 »
Dear,
     I have calculated the Mulliken population of a water molecule according to the manual. I want to know that what does this population represent for? Can this represent the electron withdrawing or donating abilities of atoms or radicals?
    Thanks a lot!

Admin edit: Confusing spelling mistake in subject

22
General Questions and Answers / band calculation of Fe FCC
« on: October 31, 2011, 06:54 »
Dear,
    When i calculate the band structure of Fe (FCC), the results show that there are three bands below the Fermi level. So i suppose that they are for the 3d6 electrons of Fe. Is this right?
   
Thanks a lot!
                                                                             Jerry

23
General Questions and Answers / electrochemical potentials of electrodes in two terminal device
« on: October 29, 2011, 04:24 »
Dear,
    When i calculate a two probe system, i find that the electrochemical potentials of electrodes shown in the transmission spectrum are the Fermi level of electrodes plus and minus 0.5*the applied voltage no matter how the left electrode voltage or right electrode voltage is set. Is this so?

24
General Questions and Answers / tolerance setting
« on: October 23, 2011, 04:44 »
Dear,
    I am a little confused by the tolerance setting in the iteration control panel. Does the tolerance correspond to total energy or other parameters?
    Thank you very much！
                                                                                Jerry

25
General Questions and Answers / Three Terminal device
« on: September 16, 2011, 03:21 »
Dear,
    I want to figure out that when a gate electrode is introduced to a three terminal device with positive gate bias, is the energy spectrum elevated or decreased relative to zero gate bias? Thanks very much! The version i use is 11.8 alpha. The boundary condition of poisson solver is Neumann. By the way, i found that the energy spectrum (MPSH for the molecule) of the three terminal device is very different from that of two terminal device without a gate electrode (molecular junction device). For instance, when a gate bias -1V is applied, the MPSH energy spectrum of a molecule is very weird, its lowest orbital can be -700eV. Is this reasonable?

26
General Questions and Answers / calculation principles
« on: August 30, 2011, 14:24 »
Dear,
    Can you provide me with the references on the calculation principles for two and three probe systems?
    Thank you very much!

    Jerry

27
Future Releases / When will be the newest ATK released?
« on: August 22, 2011, 04:41 »
Dear,
    I have used the ATK11.2.3 to calculate a device configuration with continuum dielectric regions. However, this version uses mount of memory. I want to know when the newest version of ATK will be released?
Thank you very much!

28
General Questions and Answers / error when calculate twoprobe system
« on: August 8, 2011, 14:07 »
Dear,
    When I tried to calculate the transmission and DOS for a two probe system, an error occured. The following is the clue: terminate called after throwing an instance of 'std::bad_alloc'. The OS is linux 32bit.
Can you give me some suggestion? Thanks a lot!
    Jerry

29
General Questions and Answers / error when calculating two probe system
« on: July 30, 2011, 09:45 »
Hello,
    When calculating a two probe system with a third gate electrode, an error occurs at the completion of equivalent bulk calculation stage. The former three stages converge well. Here is the error details:
  Problem signature:
  Problem Event Name:   APPCRASH
  Application Name:   atkpython.exe
  Application Version:   0.0.0.0
  Application Timestamp:   4dd1f269
  Fault Module Name:   _NLEngine.pyd
  Fault Module Version:   0.0.0.0
  Fault Module Timestamp:   4dd207fa
  Exception Code:   c0000005
  Exception Offset:   0000000000394462
  OS Version:   6.0.6001.2.1.0.274.10
  Locale ID:   1033
  Additional Information 1:   ef4f
  Additional Information 2:   39013d46dca55f118ff247d96151c1c6
  Additional Information 3:   b04e
  Additional Information 4:   9244f034639fafd7f61d319a2c03f5f2
Can you give me some advice?
Thanks a lot!

30
General Questions and Answers / K point sampling
« on: July 30, 2011, 06:02 »
Dear,
    I want to know how to sample K points in a two or three probe (with gate electrode) system. Is the K point sampling is only for the electrode? The central region is handled using non-equilibrium Green function? Can you give me some examples for three dimensional systems rather than one dimensional (atomic chain)?
   If the K point in the new calculator is set as 2*2*10(along a, b, c respectively). How to set the K point in the transmissioneigenvalues? Is the K point in the transmissioneigenvalues fractional or integral?
 Thanks a lot!

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