Topics

1

General Questions and Answers / Questions about the total energy of a twoprobe system!

« on: January 17, 2011, 16:03 »

Hello, evergyone
    For ATK-Version 2008.10 (DFT edition), the manual shows that the total energy of a twoprobe system can be calculated and it mainly include three parts: Electron kinetic energy, Electrostatic energy, and Exchange-corr. energy. However, for ATK 10.8 (DFT edition) I find that for a twoprobe system or device configuration the total energy of it is divided into four parts: Electron kinetic energy, Exchange-corr. energy, Hartree energy, and Interaction energy with the pseudo potential ions and other electro-static external potentials.
    I want to know whether Electrostatic energy of ATK-Version 2008.10 equals to the sum of Hartree energy and Interaction energy of ATK 10.8? Is that true even when bias voltage is applied?

2

General Questions and Answers / How to choose MultigridForElectrostatics method under homogeneous electrodes

« on: May 20, 2010, 09:14 »

Hi, everyone.
     I want to know how to choose MultigridForElectrostatics method to conduct calculations for a two-probe system with homogeneous electrodes. The following is my choice and is that right?
     Take Li-H2_Li as an example, I just use the same ElectrodeParameters but define the two parameters separately, that is,
==================================================================     
# Set k-points for electrodes
bz_int_param = brillouinZoneIntegrationParameters( (1,1,100) )

# Create parameters for electrodes
electrode_params_1 = ElectrodeParameters(
    brillouin_zone_integration_parameters = bz_int_param,
    iteration_control_parameters=iterationControlParameters(tolerance=1e-5,max_steps=300)
    )

electrode_params_2 = ElectrodeParameters(
    brillouin_zone_integration_parameters = bz_int_param,
    iteration_control_parameters=iterationControlParameters(tolerance=1e-5,max_steps=300)
    )   
......
method = TwoProbeMethod(
    (electrode_params_1,electrode_params_2),
    basis_set_parameters = basis_set_params,
    exchange_correlation_type = LDA.PZ,
    iteration_control_parameters = iteration_control_params,
    energy_contour_integral_parameters=energy_contour,
    algorithm_parameters=two_probe_params
    )
=====================================================================

Does it achieve the goal of using the MultigridForElectrostatics method?

3

General Questions and Answers / How to choose the IterationControl criteria??

« on: January 7, 2010, 14:34 »

Hello,
         I am confused about the iterationControl criteria and want to know their differences.
         Especially I want to know which one to choose in order to execute an efficient and reliable self-consistent calculation. 

4

General Questions and Answers / Pulay mixing inversion failed. Using only last step

« on: December 19, 2009, 13:12 »

    hello, everyone. When I calculate a isolated system more than 200 atoms, a problem happens and the message is given that "Pulay mixing inversion failed. Using only last step".
    Besides, the runtimeParameters gives:
sc 1 : Fermi Energy = 0.00000 Ry  Ebs =nan Ry dRho =0.0000E+00  dEbs = NAN Ry  dH =  0.0000E+00 Ry
......
sc 14: Fermi Energy = 0.00000 Ry  Ebs =nan Ry dRho =0.0000E+00  dEbs = NAN Ry  dH =  0.0000E+00 Ry
......

    How to deal with this problem? Thank you for any relies.

5

General Questions and Answers / About the energy resolution in Transmission Coefficients

« on: April 17, 2009, 16:35 »

Hello, everyone. I want to ask some questions about the energy resolution in Transmission Coefficients. In my calculation, Transmission Coefficients were calculated from -3eV to 3eV with the interval of 10E-4eV. Here is my puzzle, is such little interval of 10E-4eV or the  results calculated with the interval reliable ?

6

General Questions and Answers / About the molecular unit cell!!

« on: March 4, 2009, 04:00 »

Hello everyone,
       I have some questions about the the molecular unit cell. The manual tells us that the molecular unit cell is automatically chosen such that there are no matrix elements between atoms in adjacent cells. Here I want to kown what "automatically" mean and whether it is related to the basis range of elements. If it is, how do you choose the distance to ensure no matrix elements between atoms in adjacent cells?!  And could you offer data about the basis range of elements?  Thank you very much.

7

General Questions and Answers / About the parallel calculation using ATK

« on: January 11, 2009, 05:48 »

I am confused about the parallel calculation using ATK. The manual of ATK tells that if ATK is properly configured to run in parallel on your system, the test_mpi.py file should be written like that:

 from ATK.MPI import *
 
 if processIsMaster():
     print '# Master node'
 else:
     print '# Slave node'

After the following command
   
mpiexec -n 2 $ATK_BIN_DIR/atk /home/myusername/test_mpi.py

the result should  be         Master node

                                     Slave node
However, when I did the same job I got the result like that:
                                   
                                     Master node
                                   
                                     Master node

Now if I conduct a parallel job in this setting, is it still a real parallel calculation??

8

General Questions and Answers / What does 'ATKError: St9bad_alloc' mean, developer?

« on: December 29, 2008, 14:09 »

When I calculate a two-probe system, which has 313 atoms in the central region, the message 'ATKError: St9bad_alloc' always obtained after the calculation of the electrode has converged. What does 'ATKError: St9bad_alloc' really means?