dipole moment + specify HOMO and LUMO on transmission spectrum

[sayedmesa]

Dear All,

I am VNL 2008.1 user under windows XP. I have four questions:

1- Can I calculate the dipole moment of an isolated molecule using VNL?
2- I see in many papers that the Frontier MOs are shown on the transmission spectrum as small vertical lines around the Fermi energy level (zero eV). Which one can specified on transmission spectrum, molecular spectrum (of isolated molecule) or projected Hamiltonian energy spectrum (two probe system)?

3-In the context, what does mean by "energy bias" or "windows bias"? And how can I calculate it? Please give me an example for clarification.

4- In case of calculation of MPSH ( projected Hamiltonian energy spectrum), there are three points to for setting up:
(i) projected atoms (ii) include molecule atoms (iii) include surface atoms
My case: organic molecule has 32 atoms in two probe system. When I specify (ii) and leave (i) empty I found that the number of projected atoms in the script is 72 atoms and I found also the list start with zero. When I add in (i) list from 0 to 20,I found it excatly in the script. Could you please clarify this point.
Regards,
Sayed

[zh]

1. the dipole moment of an isolated molecule cannot be obtained directly by means of VNL. Additional coding is needed to integrate the charge density for the calculation of dipole moment.
2. the answer is the projected Hamiltonian energy spectrum.
3. your question of "energy bias" is not clear. Please state clearly the first part of this question. If you are asking about "bias voltage applied on two electrode", the bias voltage is just one of input parameter.

[Anders Blom]

1. Although it's not a supported feature, there are some hints about how to compute the dipole (and other) moments in the manual. See the very end of http://quantumwise.com/documents/manuals/latest/ReferenceManual/XHTML/ref.electrondifferencedensity.html