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Messages - yangzw1985

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91
General Questions and Answers / Re: transmission spectrum
« on: March 7, 2009, 14:54 »

Thank you very much. but if we use more accuracy settings, there is always something happens incidently, and the calculation failed again and again.
we wii try you suggestions.
and if you solved the problem, please tell me as soon as possible.
Thanks in advance!

92
General Questions and Answers / Re: transmission spectrum
« on: March 7, 2009, 14:35 »
what should we do if we want to solve the problem, reset the paremeters,or ?
but we also can not know our recalculated results is right or not?
So, can you check out the problem for me ? Thank you !

93
General Questions and Answers / Re: transmission spectrum
« on: March 7, 2009, 14:04 »
I have tried with the second a few days ago, but it does't works. the results are the same. I really can not find out the problem. can you check it for me as quickly as possible?
And I also need a confirm, My calculated results is right or not? thanks!

94
General Questions and Answers / transmission spectrum
« on: March 7, 2009, 13:37 »
Hi, Everyone! please have a look at the attached calculated results, In my opinion, it is not right. can anyone help check out why all of the results are almost zero? what's the matter?
Thank you!!

95
General Questions and Answers / Re: boundary conditions
« on: March 5, 2009, 12:48 »
HI, I try to answer the question, but I find its very difficult for me. can you give me more details on :What is the periodic boundary conditions of li-zno-li two probe system?

96
General Questions and Answers / Re: Where is the equlibrium fermi level ?
« on: March 2, 2009, 14:58 »
But in some transmission spectrum picture,there is a bias window referred to the energy interval from the chemical potential of the left electrode to that of the right electrode. and it is written as [-v/2,+v/2]where v is the applied voltage. if calculated transinission spectrum from -2 to +2 ,how to determine the bias window?

absolute energy you have calculated the transmission spectrum in a energy window from -16.7495 eV to 7.2505 eV.
 if i want give the transmiaaion spectrum from -6 to +6 at the X axis with E-Ef(ev), where is the fermi level ,0 or -4.7495?

if the -6 to 6ev at the x axis with E-Ef , when the fermi level=0 , Do i have to use the results from -10.7459 to 1.1205.

97
General Questions and Answers / Re: Where is the equlibrium fermi level ?
« on: March 2, 2009, 13:53 »
-0.35530 Ry=-4.7495 ev that means the fermi energy is -4.7495 ev of our two probe systerm. we have calculated the transmission spectrum 500 points from -12ev  to +12 ev. In the transmission spectrum, is the fermi energy is always equals 0 EV? I guess my pro will can not accept the answer and the reasons.

98
General Questions and Answers / Re: Where is the equlibrium fermi level ?
« on: March 2, 2009, 12:17 »
    Thank you, Anders Blom! I have told the answer to my pro, but he didn't agree with you.Can you give me sufficient reasons to help me to make my pro agree with you?
     If the frimi level=0, then what is the real mean of the fermi energy in the exported transmission spectrum is? As can we see from the exported transmission spectrum , for  Electrodes Calculation
#
 ----------------------------------------------------------------
# sc  0 : Fermi Energy =    0.00000 Ry
#-------------------------------------------------------------------------------
# Mulliken Population for sc 0
#-------------------------------------------------------------------------------
 0 Li     q =  1.00000 [ s:  1.000, py:  0.000, pz:  0.000, px:  0.000 ]
 1 Li     q =  1.00000 [ s:  1.000, py:  0.000, pz:  0.000, px:  0.000 ]
 2 Li     q =  1.00000 [ s:  1.000, py:  0.000, pz:  0.000, px:  0.000 ]
 3 Li     q =  1.00000 [ s:  1.000, py:  0.000, pz:  0.000, px:  0.000 ]
#-------------------------------------------------------------------------------
# Total Charge =    4.00000
#-------------------------------------------------------------------------------
# sc  1 : Fermi Energy =   -0.41765 Ry  dRho = 4.6383E+000
#-------------------------------------------------------------------------------
# Mulliken Population for sc 1
#-------------------------------------------------------------------------------
 0 Li     q =  0.99999 [ s:  0.476, py:  0.186, pz:  0.153, px:  0.186 ]
 1 Li     q =  1.00001 [ s:  0.476, py:  0.186, pz:  0.153, px:  0.186 ]
 2 Li     q =  1.00000 [ s:  0.476, py:  0.186, pz:  0.153, px:  0.186 ]
 3 Li     q =  1.00001 [ s:  0.476, py:  0.186, pz:  0.153, px:  0.186 ]
#-------------------------------------------------------------------------------
# Total Charge =    4.00000
#-------------------------------------------------------------------------------
# sc  2 : Fermi Energy =   -0.41572 Ry  dRho = 3.4473E-003
#-------------------------------------------------------------------------------
# Mulliken Population for sc 2
#-------------------------------------------------------------------------------
 0 Li     q =  0.99999 [ s:  0.476, py:  0.186, pz:  0.153, px:  0.186 ]
 1 Li     q =  1.00001 [ s:  0.476, py:  0.186, pz:  0.153, px:  0.186 ]
 2 Li     q =  1.00000 [ s:  0.476, py:  0.186, pz:  0.153, px:  0.186 ]
 3 Li     q =  1.00001 [ s:  0.476, py:  0.186, pz:  0.153, px:  0.186 ]
#-------------------------------------------------------------------------------
# Total Charge =    4.00000
#-------------------------------------------------------------------------------
# sc  3 : Fermi Energy =   -0.39825 Ry  Etot =   -3.70151 Ry  dRho = 3.4600E-002
#-------------------------------------------------------------------------------
# Mulliken Population for sc 3
#-------------------------------------------------------------------------------
 0 Li     q =  0.99999 [ s:  0.480, py:  0.185, pz:  0.150, px:  0.185 ]
 1 Li     q =  1.00001 [ s:  0.480, py:  0.185, pz:  0.150, px:  0.185 ]
 2 Li     q =  1.00000 [ s:  0.480, py:  0.185, pz:  0.150, px:  0.185 ]
 3 Li     q =  1.00001 [ s:  0.480, py:  0.185, pz:  0.150, px:  0.185 ]
#-------------------------------------------------------------------------------
# Total Charge =    4.00000
#-------------------------------------------------------------------------------
# sc  4 : Fermi Energy =   -0.39824 Ry  Etot =   -3.70151 Ry  dRho = 2.3260E-005  dEtot = 1.3067E-008 Ry
#-------------------------------------------------------------------------------
# Mulliken Population for sc 4
#-------------------------------------------------------------------------------
 0 Li     q =  0.99999 [ s:  0.480, py:  0.185, pz:  0.150, px:  0.185 ]
 1 Li     q =  1.00001 [ s:  0.480, py:  0.185, pz:  0.150, px:  0.185 ]
 2 Li     q =  1.00000 [ s:  0.480, py:  0.185, pz:  0.150, px:  0.185 ]
 3 Li     q =  1.00001 [ s:  0.480, py:  0.185, pz:  0.150, px:  0.185 ]
#-------------------------------------------------------------------------------
# Total Charge =    4.00000
#-------------------------------------------------------------------------------


AND AS FOR Equivalent Bulk Calculation (Initial Density for TwoProbe)

sc 23 : Fermi Energy =   -0.35530 Ry  Etot = -7301.92848 Ry  dRho = 3.8679E-004  dEtot = -6.0960E-006 Ry

can you explain the feimi energy for me ?   

thanks!!
     

99
General Questions and Answers / Where is the equlibrium fermi level ?
« on: March 2, 2009, 08:37 »
hellow,everyone! can anyone tell me where is the equlibrium fermi level of a two probe system. and how to determine the fermi energy of the two probe system from a calculated transmission spectrum? Thanks!

100
General Questions and Answers / calculate time
« on: February 23, 2009, 02:26 »
I have calculated the transimission spectrum of a li-znonanowire-li system. 500 points from -12ev to +12 ev. But the results can not be received in a long time. Can anyone tell me if the points are inappropriate? can I reduce the calculate time If I decrease the points to 200 ? If not, what should I do in order to reduce the calculate time with the same accuracy ? Thanks !

101
General Questions and Answers / about E and E-Ef
« on: February 20, 2009, 14:08 »
hellow,everyone! In the transimission spectrum, along the X axis we can always see Electron energy(ev) or E-Ef(ev). In the Y axis , they are the same as T(E). what is the difference between the two descriptions? if I calcullate the transimission spectrum with 200 points from -6ev to +6ev ,and the fermi energy is -0.3Ry. How should I determine the X axis? Moreover, can I get some information about the HOMO-LUMO from the transimission spectrum?
1 Ry =13.59 Ev!

Thanks!

102
General Questions and Answers / Re: How to improve the accuracy of the results?
« on: February 20, 2009, 11:57 »
Yes, this time is right.
Thanks!


103
General Questions and Answers / Re: How to improve the accuracy of the results?
« on: February 20, 2009, 11:12 »
if I want to calculate the transimission spectrum of a li-znowire-li with 200 points -6--6 ev, what should I do ?

there is something with my code exhibited in the screen.
For your code, the error was occured in the second lines.

energies = transmission_spectrum.energies()
coefficients = transmission_spectrum.coefficients()


electron_transmission should be changed by transmission_spectrum

Is that right?


104
General Questions and Answers / Re: How to improve the accuracy of the results?
« on: February 20, 2009, 11:05 »
But it really is !
we have check my code with li-h2-li,it is right.
but in your code ,it has an error.

105
General Questions and Answers / Re: How to improve the accuracy of the results?
« on: February 20, 2009, 10:53 »
Thank you ! Great!
But it has an error, we have corrected it. It should be like this:


energies = transmission_spectrum.energies()
coefficients = transmission_spectrum.coefficients()
print 'Energy (eV)     Transmission'
print '-----------------------------------'
for i in range(len(energies)):
    print "%g\t%g" % ( energies.inUnitsOf(eV),coefficients )

Moderator note: This code doesn't work :)

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