Hi.
if you want to proper describe correctly the charge density and
wavefunction, that means describing localized electrons (d or f), of
transition metal oxides you have to go beyond the local density
approximation of DFT (this holds even for GGA).
Otherwise if u want to describe an insulating phase of such compound in
LDA or GGA you will get instead a metallic density of state.
You will not be able to open correctly a gap, to correctly reproduce the
occupation of such localized orbitals and their correct energy ordering
for example. (this holds for several paradigmatic TMO)
Also in the metallic phase you will get metal, correct, but with an
almost incorrect redistribution of spectral weight in the density of state.
To better describe the electronic structure of such compound you have
two chances:
1. to use a hybrids functional scheme with screened range separation
(liek HSE06) to have a first proper description of the insulating and
metallic electronic structure + G0W0 calculation on top of this to
better describe the screening of your system
2. to face the problem directly using many body perturbation theory. In
the specific the approach could be to use a SelfConstistent GW scheme or
CoHSEX + G0W0.
have a look at
Phys. Rev. B 85, 115129 – Published 28 March 2012
Phys. Rev. Lett. 99, 266402 – Published 28 December 2007
for example.
Coming ti your question: in the gpl version of Siesta still there is no
GW scheme implemented. If I am not wrong neither HSE06 are implemented.
VASP and pwscf have both.
VASP all in one. PWSCF have HSE06 and is optimally interfaced with YAMBO
a code to perform many body calculations.
Hope to have been clear.
Ciao
federico
On 04/03/2014 07:07 PM, Wei Hu wrote:
Hi,
How about the SIESTA calculation of transition metal or lanthanide metal oxide
compared with VASP or pwscf? Including computing time and accuracy.
I have found few works about this respect. Why?
Best,
Wei
--
Dr. Wei Hu
Postdoc
Computational Research Division
Lawrence Berkeley National Laboratory
Berkeley, CA 94720, USA
Phone: +1-510-541-6034
E-mail: whu@@lbl.gov
Ph.D
Department of Chemical Physics
Hefei National Laboratory for Physical Sciences at the Microscale
University of Science and Technology of China
Hefei, Anhui 230026, P.R.China
Phone: +86-551-63606428
Mobile: +86-159 0560 4040
E-mail: [email protected]
--
Dr. Federico Iori, PhD!
Dipartimento di Scienze e Metodi per l' Ingegneria (DISMI)
Universita' di Modena e Reggio Emilia
Via Amendola,2
Pad. Morselli
42122 Reggio Emilia (Italy)
