[Wien] some basic queries

[Lyudmila Dobysheva]

20.03.2017 22:11, Dr. K. C. Bhamu wrote:
> 1. I want to updated Gmax and R-MT*K-MAX after initialisation.
> whether I need to redo the initialisation with
> updated parameters or I can proceed without initialisation with updated
> parameters?

These parameters do not require re-initialization.
In case when you change, for example, Rmt for some atoms, the density 
found in the previous calculation will be often worse than an atomic one 
from initialization. In such cases I prefer to make the clmextrapol 
procedure with its proper adjusting.

> 2. When we report results in the paper, we report upto maximun 3rd digit
> after fraction.
> My query is that, if the number in any property (band Gap, Fermi Ene,
> dielectric constant, etc.) is not useful after 3rd digit (as we do not
> report after it) then upto what accuracy we need to to run scf for -ec
> and -cc? Is the number -ec 0.0001 and -cc 0.0001 okay?

This depends on your concrete task: the system under study, the quantity 
that you calculate, and this is a huge part of our work: to find the 
correct way of calculation. In one of my papers (J of All. and Comp. 
2015) I considered it useful to show the whole process for isomer shift 
for which even 0.001% of electron density is important. I'd say such an 
approach should be used for other properties.

> 3. I am running a case of ternary compound (CdCo2O4) for FM calculation.
> I am doing vol optimisation with rmt 7% reduction and -fc is 2 and Gmax
> is 16.
> In this case forces are not conversing, the forces are oscillating
> between ~160 to ~200 mRd au^-1.
> What should I do so that I can get forces less that 2 mRd au^-1?

Don't know, I suspect that you mix finding "the electron density with 
the convergence criterion -fc 2" and finding "the atomic equilibrium 
with forces less than 2". So, make a separate question with details if 
my words are not enough.

Best wishes
   Lyudmila Dobysheva
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