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Re^2: Is there a Simple way to know HOMO-LUMO gap?

Siddheshwar Chopra
sidhusai@gmail.com

Dear Alexei,
I am actually running HESSIAN calculations. I looked for the string "EIGENVECTORS", and then nos. 149 and 150. But I still failed to get the HOMO-LUMO... I am atatching herewith a sample fiel for your reference. Please let me know the value of HOMO-LUMO from it..

Regards,



On Mon Feb 4 '13 11:38pm, Alexei Popov wrote
--------------------------------------------
>Hello,

>this can be done very simple.

>Run single point SCF energy calculation. Look at the output and you'll see strings like these:

> TOTAL NUMBER OF SHELLS              =   10
> TOTAL NUMBER OF BASIS FUNCTIONS     =   38
> NUMBER OF ELECTRONS                 =   12
> CHARGE OF MOLECULE                  =    0
> STATE MULTIPLICITY                  =    1
> NUMBER OF OCCUPIED ORBITALS (ALPHA) =    6
> NUMBER OF OCCUPIED ORBITALS (BETA ) =    6

>Orbital #6 is HOMO and orbital #7 is LUMO.

>Look at the section

> FINAL ENERGY IS....
>
>
>          ------------
>          EIGENVECTORS
>          ------------

>and find the eigen-vectors #6 and #7 (they are numbered so it is easy)
>The numbers above the eigen-vectors are their energies. Substract two numbers for two orbitals and you'll get the answer.

>Cheers,
>Alexei Popov
>
>
>
>On Mon Feb 4 '13 12:41pm, Siddheshwar Chopra wrote
>--------------------------------------------------
>>Dear Sir,
>>Please forgive me for asking this question perhaps again in this forum. Actually I have completed the HESSIAN run and am able to read the HOMO,LUMO energies USING GABEDIT software. But I find it really too involving and error prone to calculate the HOMO-LUMO gap from the data. Please suggest em a simpler way so that I get the HOMO-LUMO gap directly...IS there any COMMAND I could add in the FIREFLY input file to get HOMO-LUMO printed in the output file directly?
>>If a command line input is not available, can Prof. Alex add ONE such command for the users?

>>Regards,

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