[Wien] Fundamental Question regarding Structure Optimization

[shamik chakrabarti]

Dear wien2k users,

              I have a fundamental question regarding structure
optimization. Say, we optimize structure of a system by two following paths:

(A) We first optimize volume and lattice parameters & after that the
optimized structure is used as input for force optimization. Finally, we
achieve a optimized structure with very less force associated with each
atom.

(B) We optimize lattice parameter and force/atom simultaneously (by using
MSR1a - which is tediously time consuming and some times never ending....
as we have seen from our experience). Also in this path we have achieved a
structure with very less force (comparable to Path A) associated with it.

Hence, we can have two solutions of optimized structure along two different
path. Now, which one is ground state solutions (probably through Path B)
can be known by comparing energy corresponding to both solutions.

Now, probably Path A will bring the actual minima while Path B will bring a
"false" minima.

Now, my question is

As the electronic structure of a system depends very much on the strain of
atomic bonds and as both structures have very less and comparable force
associated with each atoms, can the electronic structure obtained from Path
B be a close approximation of that obtained with Path A?...

(I am asking this question as Path B is so much tedious and time
consuming...that it is difficult to go through Path B in real time scale
for a large system)

Also, if any reference regarding the relations between geometric and
electronic structure are available kindly let me know the same.

Thanks in advance,

with regards,

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