QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: yangzw1985 on February 20, 2009, 14:08

Title: about E and E-Ef
Post by: yangzw1985 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!

Title: Re: about E and E-Ef
Post by: Anders Blom on February 20, 2009, 14:40

When ATK calculates the transmission spectrum, the energies are always shifted such that the Fermi level corresponds to E=0. Therefore, E and E-Ef is the same, since Ef=0.

HOMO and LUMO are by definition not well-defined in the non-equillibrium case, however you can compute the MPSH spectrum to find information about the corresponding molecular-like levels. Some more information is available in the manual on Li-H2-Li (http://quantumwise.com/documents/manuals/ATK-2008.10/chap.advtwoprobe.html), also you can search the Forum for "MPSH" for some other relevant posts.