HOMO-LUMO/Spin Gap

[eden_anteneh]

Hi, I'm a new user of VASP . I have question that confuse me.
1) I want to calculate spin-gap. So I chose for majority channel(HOMO E = -3.8066, LUMO E = -3.3506) and minority channel (HOMO E = -3.6543, LUMO E = -3.5312) from the output shown below, Am I correct? Here is my OUTPUT. I got the following using homolumo script.
Number of Bands = 96
k-point 1 : 0.0000 0.0000 0.0000 HOMO = 74 E = -3.8066 LUMO = 75 E = -3.3506 BandGap = -0.456
HOMO = 75 E = -3.3506 LUMO = 76 E = -1.4497 BandGap = -1.9009
k-point 1 : 0.0000 0.0000 0.0000 HOMO = 31 E = -3.6543 LUMO = 32 E = -3.5312 BandGap = -0.1231
HOMO = 32 E = -3.5312 LUMO = 33 E = -3.5157 BandGap = -0.0155000000000003
HOMO = 33 E = -3.5157 LUMO = 34 E = -3.5052 BandGap = -0.0105
HOMO = 34 E = -3.5052 LUMO = 35 E = -3.2987 BandGap = -0.2065
HOMO = 35 E = -3.2987 LUMO = 36 E = -3.2889 BandGap = -0.00980000000000025
HOMO = 36 E = -3.2889 LUMO = 37 E = -3.2300 BandGap = -0.0589
HOMO = 37 E = -3.2300 LUMO = 38 E = -3.2220 BandGap = -0.00800000000000001
HOMO = 38 E = -3.2220 LUMO = 39 E = -3.1835 BandGap = -0.0385
HOMO = 39 E = -3.1835 LUMO = 40 E = -2.9132 BandGap = -0.2703
HOMO = 40 E = -2.9132 LUMO = 41 E = -2.9065 BandGap = -0.00669999999999993

From the above output how could I choose the HOMO-LUMO to calculate the spin-gap?

If some one can help me, I would appreciate very much
Anteneh

[graeme]

This forum is only for transition state theory related questions.

But anyway, if you want the gap between a single and triplet state, you can just do a single calculation and then a triplet calculation and subtract the energy differences.

[eden_anteneh]

Thank You Mr graeme.
Do you mean that the VTST script is not working for cluster like Fe_13 etc?
I am using the script to extract information from my OUTPUT, especially for DOS and PDOS calculation.
Am I wrong?

Thanks in advance,
Anteneh

[graeme]

My initial comment just means that this forum is related to vasp transition state theory (VTST) methods. Finding a gap is not related to a transition state -- you can ask your question to the regular vasp forum at: http://cms.mpi.univie.ac.at/vasp-forum/forum.php