[Wien] Extraction of atomic sphere potential

[Peter Blaha]

VZERO is certainly only a small contribution, but you also have the 
Hartree and the XC potential.

2 more comments: In the scalar relativistic approximation, the 
s-wavefunction diverges at the nucleus (contributing to some 
Hartree-potential) and in particular r0 (the first radial mesh-point) 
can be different for different atoms (r0 is much larger for light atoms 
and much smaller for heavier ones. In any case, even the smallest r0 
(1^-5 bohr) is not quite zero and extrapolation to r=0 is difficult.

You can use R2V in case.in0 and look at Coulomb (nuclear + Hartree) and 
V-XC individually. (Be careful when plotting with lapw5. it does a 
linear interpolation between r-points, but also an extrapolation from r0 
to zero, which can be very wrong, it is better to plot the r2v 
potentials using directly the radial mesh).

Am 01.07.2023 um 01:24 schrieb Artem Tarasov via Wien:
> Dear Prof Peter Blaha,
>
> If possible, I would like to discuss another question regarding 
> MT-potentials. I am currently trying to work with them using .vsp and 
> .vtotal files. From general considerations it seems obvious that the 
> dependence V(r)*r in the hartree/bohr axes should take the Z value for 
> a given atom when r approaching the nucleus. However, I see that the 
> values, to which the potentials from these files tend to, differ to 
> some degree from Z. And this difference is not equal to VZERO (which 
> was my first attempt to explain what happens). And at all I am puzzled 
> by the fact, that when one considers the calculation of a unit cell, 
> consisting of different atoms, potential of each of them differs from 
> corresponding Z by its own value. Could you please explain to me the 
> reason for this?
>
>
> Best regards,
> Artem Tarasov
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Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
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Email: peter.blaha at tuwien.ac.at
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