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QuantumATK => General Questions and Answers => Topic started by: njuxyh on January 7, 2011, 15:03

Title: four question about mpsh calculation
Post by: njuxyh on January 7, 2011, 15:03
hi : every one
i have some question about mpsh calculation:
1) if i have many projection_atoms in calculateProjectedHamiltonianEigenstates funtion, beside i wrote one by one such as below, can i write a loop in python language, how to write in script?
2) i have searched the forum, and found MPSH is only suitable molecular in scattering region , not for the nanowire in scattering region? is it true? and why?
3) the mpsh analysis is better for the molecular only  (Zh answer), but others says if the molecular interact with sufacelayer atoms strongly , it should include some surfacelayer atoms.  so i am confusing.
4) i have two quantum _numbers to concern. one is the first one below zero energy. and another is the first one above the zero. (i think, they are related the transport in Ef (no bias condition)? but when i watch the 3D plot of the  mpsh, i thought, it should have two Eigenstates( the two i set above), but i only saw one  Eigenstates. why ?
   
maybe my question is foolish. i would like some idear to clarify.

calculateProjectedHamiltonianEigenstates(
    self_consistent_calculation = scf,
    projection_atoms = (72, 73, 74, 75……), 
    quantum_numbers = (547,548,549,550,551,552,553,554,)
Title: Re: four question about mpsh calculation
Post by: Anders Blom on January 10, 2011, 16:41
hi : every one
i have some question about mpsh calculation:
1) if i have many projection_atoms in calculateProjectedHamiltonianEigenstates funtion, beside i wrote one by one such as below, can i write a loop in python language, how to write in script?
Sure, there are many ways you can simplify the setup of the projection list. In the end, it just needs to be a list (or tuple) of integers. So, just as an example, you could use for your example
Code: python
p_atoms = range(72,76)
calculateProjectedHamiltonianEigenstates(
    self_consistent_calculation = scf,
    projection_atoms = p_atoms, 
    quantum_numbers = (547,548,549,550,551,552,553,554,)
2) i have searched the forum, and found MPSH is only suitable molecular in scattering region , not for the nanowire in scattering region? is it true? and why?
The purpose of the MPSH spectrum is usually to compare with the corresponding spectrum of the molecule in vacuum. For the nanowire, you don't really have such a comparison spectrum. It may be more relevant, in that case, to compare the density of states, for example.
3) the mpsh analysis is better for the molecular only  (Zh answer), but others says if the molecular interact with sufacelayer atoms strongly , it should include some surfacelayer atoms.  so i am confusing.
If only using the molecule you may miss a lot of contributions to the Hamiltonian of the molecule, if it is strongly coupled to the surface layers.
4) i have two quantum _numbers to concern. one is the first one below zero energy. and another is the first one above the zero. (i think, they are related the transport in Ef (no bias condition)? but when i watch the 3D plot of the  mpsh, i thought, it should have two Eigenstates( the two i set above), but i only saw one  Eigenstates. why ?
Not sure. You will have as many eigenstates in the NC file as you have quantum_numbers in the script.