[Wien] LCAO vs. LAPW

[Peter Blaha]

The LMTO calculations use the ASA approximation (overlapping spheres, 
but no representation of wavefunctions in the interstital).

It was used a lot when computers were slow, but nowadays ASA-LMTO is not 
state of the art. (There are also some full-potential LMTO versions 
around nowadays, which should be ok).

Also the Moruzzi paper is NOT an LCAO calculation, but uses the ASW 
method, which is nearly identical to the ASA-LMTO method.

I'm not surprised that you see some differences.

Am 14.05.2010 11:04, schrieb Lukasz Plucinski:
> Dear WIEN2k Users and Experts,
>
> Would it be possible to get some comment to my email from April 30 ? See
> below.
>
> Regards,
>
> Lukasz
>
>
> Lukasz Plucinski wrote:
>> Dear Wien2k users,
>> (I am sending the same email with smaller attachment, because of the
>> 40kB attachment limit)
>>
>> I have calculated ferromagnetic FeRh according to the parameters from
>> Koenig et al. J. Phys. F 12, 1123 (1982). Its CsCl lattice, with
>> (0,0,0) and (a/2, a/2, a/2) positions with 2.985 A lattice constant. I
>> used all default WIEN2k settings.
>>
>> I obtained slightly different band positions, see attached figure. My
>> DOS is also slightly different than Koenig et al, and another LCAO
>> calculation of Moruzzi et al. PRB 46, 2864 (1992). Shape of the DOS
>> and even the y-scale [states/eV] values agree, but there are slight
>> shifts in energy, maybe up to 0.5 eV for some parts.
>>
>> Are differences of this order something expected between LMTO and LAPW ?
>>
>> I also noticed a recent paper on merging LAPW with LMTO subject: by
>> Kotani and Schlifgaarde http://prb.aps.org/abstract/PRB/v81/i12/e125117
>>
>> Regards,
>>
>> Lukasz
>>
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>>
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-- 
Peter Blaha
Inst.Materialchemie, TU Wien
Getreidemarkt 9
A-1060 Vienna
Austria