exercise/05: Mixing enthalpy for bcc FeCrx alloy: PM

In this exercise we will practice how to treat magnetic disorder with CPA. It is the same story as exercise/04[1], but here we treat the system within paramagnetic (PM) state.

\[H = E_{Fe^\uparrow_{(1-x/2)}Fe^\downarrow_{(1-x/2)}Cr^\uparrow_{x/2}Cr^\downarrow_{x/2} } - ( 1-x )E_{Fe^\uparrow_{50}Fe^\downarrow_{50}} - x E_{Cr^\uparrow_{50}Cr^\downarrow_{50}}\]

  • copy kgrn and kfcd input form exercise/04 and reuse its kstr, bmdl and shape.

    cp -r ../04/{kgrn,kfcd} 05/
cd 05
ln -s ../04/kstr
ln -s ../04/bmdl
ln -s ../04/shape
cp kgrn/{fecr_FM,fecr_PM}.dat
cp kfcd/{fecr_FM,fecr_PM}.dat

  • spin \(\uparrow\) and \(\downarrow\) as “alloy components”.

    split the components to half in kgrn input
    27Symb   IQ IT ITA NZ  CONC   Sm(s)  S(ws) WS(wst) QTR SPLT Fix
28Fe      1  1  1  26  25.00  0.000  1.000  1.000  0.0  2.0  N
29Fe      1  1  2  26  25.00  0.000  1.000  1.000  0.0 -2.0  N
30Cr      1  1  3  24  25.00  0.000  1.000  1.000  0.0 -1.0  N
31Cr      1  1  4  24  25.00  0.000  1.000  1.000  0.0  1.0  N

    • remember change MNTA.=  4.

  • add “atomic config” for the extra components.

    37Fe
38Iz=  26 Norb= 10 Ion=  0 Config= 3d7_4s1
39n      1  2  2  2  3  3  3  3  3  4
40Kappa -1 -1  1 -2 -1  1 -2  2 -3 -1
41Occup  2  2  2  4  2  2  4  4  3  1
42Valen  0  0  0  0  0  0  0  1  1  1
43Fe
44Iz=  26 Norb= 10 Ion=  0 Config= 3d7_4s1
45n      1  2  2  2  3  3  3  3  3  4
46Kappa -1 -1  1 -2 -1  1 -2  2 -3 -1
47Occup  2  2  2  4  2  2  4  4  3  1
48Valen  0  0  0  0  0  0  0  1  1  1
49Cr
50Iz=  24 Norb=  9 Ion=  0 Config= 3d4_4s2
51n      1  2  2  2  3  3  3  3  4
52Kappa -1 -1  1 -2 -1  1 -2  2 -1
53Occup  2  2  2  4  2  2  4  4  2
54Valen  0  0  0  0  0  0  0  1  1
55Cr
56Iz=  24 Norb=  9 Ion=  0 Config= 3d4_4s2
57n      1  2  2  2  3  3  3  3  4
58Kappa -1 -1  1 -2 -1  1 -2  2 -1
59Occup  2  2  2  4  2  2  4  4  2
60Valen  0  0  0  0  0  0  0  1  1

  • calculations and results processing are same as exercise/04