[Wien] Fwd: A question regarding unusual DOS pattern

[shamik chakrabarti]

---------- Forwarded message ----------
From: shamik chakrabarti <shamikphy at gmail.com>
Date: Thu, Jul 12, 2012 at 3:43 AM
Subject: A question regarding unusual DOS pattern
To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>


Dear wien2k users,

                           We have simulated DOS of a Li based oxide
material. Although, there is band gap across Fermi energy for atomic DOS of
transition metal atom presents in the alloy, atomic DOS of Li is
significant and continuous across Ef. It seems from the total DOS and
atomic DOS of Li that the alloy can behave as a half metal due (DOS is
connected from valance band to conduction band through spin dn channel) to
Li atom which should be wrong.

However, from the total energy calculation we have calculated Li
intercalation voltage which is matching very closely with experimental
value (with a 200 mV overestimation which is considered to be small in this
type of calculation).

This calculation was done using experimental structural parameters and
without doing geometrical optimization due to presence of large number of
atoms in the unit cell. *There is also large force appearing on the Li
atoms (around 100 mRy/a.u.). However, again I insist on the fact that the
Li intercalation voltage from the same calculation giving very accurate
value. *

My question is: (1) Whether the appearance of Li DOS across Fermi energy
may have its origin in the fact of not having done the geometrical
optimization which is the cause of strained Li-O bond?

(2) OR appearing of Li DOS across Ef may consist of some different Physics?

It is true that we may tell the answer properly after doing the geometrical
optimization...but before starting that huge job (!)...any response in this
regard will be very helpful for us.

Thanking you,
-- 
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA



-- 
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA
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