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O(N) method in Openmx
Date: 2014/09/01 05:59
Name: Chen

Dear Prof. Ozaki,

I am very interested in the O(N) method of Openmx. The capability of dealing with more than ten thousand atoms is very impressive. I am now studying a junction structure with plane-wave method but the computational demand is huge (the number of atoms > 5000). I am trying to use the O(N) methods (DC,Krylov,low-order scaling) in Openmx. If I understand correctly, there is a compromise between accuracy and efficiency for O(N) method. For the junction structure, e.g. Fe/GaAs junction, the relative alignment of Fermi levels of Fe and GaAS is quite important for me. If I use the conventional band structure method, it is not difficult to determine the Fermi level since we can fill up the electronic states until the number of electrons is reached.

I am wondering if O(N) method can predict the position of the Fermi level of a material (e.g. bulk) accurately. Will the Fermi level change with the choice of input parameters, i.e. the cluster size? If one of your paper has already mentioned this point, please tell me.

Thanks a lot.

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Re: O(N) method in Openmx ( No.1 )
Date: 2014/10/27 22:41
Name: T. Ozaki


In order to determine the Fermi level, you can combine both the O(N) and conventional
diagonalization methods as explained at

Recent papers on application of the O(N) may give a crue on how the O(N) can be applied
for your system:
T. Ohwaki et al., J. Chem. Phys. 140, 244105 (2014).
T. Ohwaki et al., J. Chem. Phys. 136, 134101 (2012).
H. Sawada et al., Modelling Simul. Mater. Sci. Eng. 21, 045012 (2013).
N. Ileri et al., Theo. Chem. Accounts 133, 1575 (2014).

Best regards,


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