Messages

1

General Questions and Answers / charge transfer

« on: August 5, 2013, 02:06 »

Hi,professor:
 we always calculate the charge transfer by ATK , in my paper, i calculate the scattering region charge transfer with the increase of bias voltage,but the reviewer refuse to accept my paper for the reason that "ATK uses the NEGF-DFT framework originally developed in McGill University, which assumes always keeping the charge neutrality of the whole central scattering region, at even non-equilibrium, i.e. there is no charge transfer at the boundary between lead and central region and the Hartree potential at the boundary should be continuous."  which means ATK can not calculate the charge transfer and without any meaning?
thank you!

2

General Questions and Answers / Re: what is the physical meaning of electrostatic potential contour

« on: November 30, 2012, 12:33 »

thanks a lot!  but it is not the voltage drop,it is the  the electrostatic difference potential under zero bias. so i donot think it is phsical meaning of "why the region is yellow on left side while red on the right side around the molecular, however it is opposite on the molecular."

3

General Questions and Answers / what is the physical meaning of electrostatic potential contour

« on: November 28, 2012, 03:21 »

I plot the electrostatic potential contour, but I don’t know what is the physical meaning of the picture. Anders Blom told the electrostatic difference potential is the solution to the Poisson equation where on the right-hand side you have the electron difference density, which is the (total) electron density minus the density of the neutral atoms on this forum.
In my picture, why the region is yellow on left side while red on the right side around the molecular, however it is opposite on the molecular. Can anybody tell me the physical meaning of the picture?

4

General Questions and Answers / Re: About the bond length of Carbon and Gold in a chain

« on: October 29, 2012, 14:24 »

thanks for zh:
i have calculate the total energy of carbon chain, the result as follow:
     1.0         1.39         1.4          1.425        1.5           2.0            2.9(A)
-149.029   -155.269   -155.226   -155.097   -154.591   -151.456    -149.227
so i should chose the 1.39(A) for the Carbon chain, right? but why you chose the 2.9? or it will affect the result chose different length?

5

General Questions and Answers / Re: About the bond length of Carbon and Gold in a chain

« on: October 28, 2012, 16:34 »

thank you for you answering. if i set  the bond length to 1.4A, it means that the system is unpolarized? another question occur, how to decision the bond length if i want to use the carbon chain as electrode. in other chain, such as Gold or Iron, whether it need to be set the length longer than its the lattice constant for a spin systems?

6

General Questions and Answers / About the bond length of Carbon and Gold in a chain

« on: October 28, 2012, 03:39 »

in atk tutorials, the bond length of C-C  is 2.9A in a carbon chain, but the actual length is 1.4A. so, i want to know how to set the length in a chain(such as gold(2.88) ) .

7

General Questions and Answers / Re: how to achieve self-consistent

« on: September 19, 2012, 14:57 »

thanks for your explain! i have follow your advise,but it still can't SCF. What else can I do?

8

General Questions and Answers / Re: how to achieve self-consistent

« on: September 18, 2012, 01:54 »

thank you for you answer!but This is a system work can't change the structure, and other cases it can be well self-consistent in the same parameters."SingleContour instead of DoubleContour"is meaning using the DoubleDZetaPolarized. but my computer memory is not enough when i using the  DoubleDZetaPolarizedinstead ofsingleDZetaPolarized? Are there any other way?

9

General Questions and Answers / Re: how to achieve self-consistent

« on: September 17, 2012, 15:47 »

i am sure that my electrodes are 1-dimensional.I have use the previous SCF result as an initial state for SCF(from 0,1.5,0.1).but it can't SCF when the voltage above 0.6.if you need the input file,i can post you by e-mail.

10

General Questions and Answers / how to achieve self-consistent

« on: September 17, 2012, 14:26 »

it can be well self-consistent below 0.4 voltage, however it cann't be self-consistent  above 0.6 voltage in my system(tolerance=0.00008). i have change some parameters, such as:grid_mesh_cutoff, circle_points=50,real_axis_infinitesimal=0.0005*Hartree, integral_lower_bound=5.0*Hartree, Maybe it is wrong.so i need you help me!. thank you!
i provide the export file.log under 1.2 voltage,if you want the input file, i can provide by E-mail.

11

General Questions and Answers / Re: urgent problem

« on: June 7, 2012, 10:47 »

so ,if i just have the 0.nc, can modify this script to realized use self-consistent result(0.2.nc) of 0.2V bias to calculate the 0.3V bias properties? because every bias have a bias.nc file.

12

General Questions and Answers / Re: urgent problem

« on: June 7, 2012, 10:11 »

i know that, i just want to know this script can be realized  the former self-consistent calculation result. such as, use self-consistent result(0.2.nc) of 0.2V bias to calculate the 0.3V bias properties? thank you!

13

General Questions and Answers / urgent problem

« on: June 7, 2012, 07:54 »

i want to know this script can be use  the former calculation result. such as we can use 0.2V self-consistent result to calculate the 0.3V properties? i found this script just using the zero bias  self-consistent result or just DeviceConfiguration. thank you!


#read in the old configuration
device_configuration = nlread("li-h2.nc",DeviceConfiguration)[0]
calculator = device_configuration.calculator()

# Define bias voltages
voltage_list=[0.1,0.2, 0.3, 0.4]*Volt
#make loop
for voltage in voltage_list:
    # Set new calculator with modified electrode voltages on the configuration
    # use the self consistent state of  the old calculation as starting input.
    device_configuration.setCalculator(
          calculator(electrode_voltages=(0*Volt, voltage)),
          initial_state=device_configuration)

    # Calculate the transmission spectrum
    transmission_spectrum = TransmissionSpectrum(
        configuration=device_configuration,
        energies=numpy.linspace(-5,5,100)*eV,
        )

    nlsave('li-h2.nc', transmission_spectrum)

14

General Questions and Answers / Re: how to change the parameter

« on: June 5, 2012, 02:49 »

in two proble system, i calculate the voltage from 0 to 1.5, but it can't self-consistent above 0.7V. and i don't know how to using the result of former converged  cased, because the analysis from the file just analyze the properties under the same bias.

15

General Questions and Answers / how to change the parameter

« on: June 4, 2012, 16:27 »

how to change the parameter  when it can not self-consistent under high bias, however, it can well self-consistent under small bias(atk12.2).thank you!