Isomer shift of Moessbauer spectroscopy

Posted on : September 03, 2018 (Mon) 20:41:47

by 池田敦俊

Dear AkaiKKR users,

I want to calculate the isomer shifts of some tin compounds.
Is "charge density at the nucleus" in the go calculation the right one to consult?

So far, I calculated SnF4, BaSnO3, SnCl4, SnSe2, Mg2Sn, beta-Sn, SnSe, and SnCl2.
However, the charge densities of SnCl4, SnSe, and SnCl2 are away from the linear tendency in the plot of the density vs isomer shift.
Is it because the numbers of atoms are large or the symmetries are low?
I used ewidth=3.0 Ry and bzqlty=4 for all calculations.
I also tried with bzqlty=3 for SnSe and SnCl2 because their unit cells are large, but the densities do not change much.
Do you have any idea to improve the calculation?

The reported isomer shifts and calculated charge densities are:
name isomer shift charge density
SnF4 -0.36 mm/s 190391.7696
BaSnO3 0 mm/s 190373.3957
SnCl4 0.85 mm/s 190390.7525
SnSe2 1.36 mm/s 190310.2726
Mg2Sn 1.86 mm/s 190271.3191
SnSe 3.31 mm/s 190308.2927
SnCl2 4.06 mm/s 190323.751

The most likely cause may be my mistake in the input file.
The input for, for example, SnSe is
c----------------------SnSe----------------------------------
go SnSe/SnSe
c------------------------------------------------------------
c brvtyp a c/a b/a alpha beta gamma
so 21.7318 , 0.386609 , 0.361217 , , , ,
c------------------------------------------------------------
c edelt ewidth reltyp sdftyp magtyp record
0.001 3.0 sra pbe nmag 2nd
c------------------------------------------------------------
c outtyp bzqlty maxitr pmix
update 4 500 0.03
c------------------------------------------------------------
c ntyp
2
c------------------------------------------------------------
c type ncmp rmt field mxl anclr conc
Se 1 1.00 0.0 2 34 100
Sn 1 1.00 0.0 2 50 100
c------------------------------------------------------------
c natm
8
c------------------------------------------------------------
c atmicx atmtyp
0.35590a 1/4b 0.01640c Se
0.64410a 3/4b 0.98360c Se
0.14410a 3/4b 0.51640c Se
0.85590a 1/4b 0.48360c Se
0.11800a 1/4b 0.10430c Sn
0.88200a 3/4b 0.89570c Sn
0.38200a 3/4b 0.60430c Sn
0.61800a 1/4b 0.39570c Sn
c------------------------------------------------------------
end

Sincerely,
Ikeda