Example: Broken spin-symmetry: Fe4S4¶

Download Fe4S4_BrokenSymm.run

This calculation shows a spin-flip restart feature that allows to exchange alpha and beta fit coefficients for selected atoms upon restart. First the high spin configuration with 8 more \(\alpha\)-electrons than beta-electrons is calculated (S_z =4). Next the broken spin-symmetry configuration is calculated (S_z =0), using the subkey spinflip in the restart key. In this case the spin will be flipped for iron atoms 1 and 2. Note that the used symmetry C(2v) is lower than the actual symmetry T(d), such that iron atoms 1 and 2 can have a different spin than iron atoms 3 and 4.

$ADFBIN/adf <<eor
TITLE Fe4S4 High-spin configuration
ATOMS
 Fe      -0.000000000000      -1.256142548900       0.888226914500
 Fe       0.000000000000       1.256142548900       0.888226914500
 Fe      -1.256142548900       0.000000000000      -0.888226914500
 Fe       1.256142548900      -0.000000000000      -0.888226914500
  S      -1.845393493800       0.000000000000       1.304890253400
  S       1.845393493800      -0.000000000000       1.304890253400
  S      -0.000000000000      -1.845393493800      -1.304890253400
  S       0.000000000000       1.845393493800      -1.304890253400
END

Symmetry C(2v)

CHARGE 0.0 8.0
UNRESTRICTED

BASIS
type DZ
core Large
createoutput None
END

XC
GGA OPBE
END
end input
eor

mv TAPE21 Fe4S4-high-spin.t21

$ADFBIN/adf <<eor
TITLE Fe4S4 LOW-spin configuration

Restart Fe4S4-high-spin.t21 &
! Make sure atoms specified in the SpinFlip keyword are symmetry-equivalent
  SpinFlip 1 2
End

ATOMS
 Fe      -0.000000000000      -1.256142548900       0.888226914500
 Fe       0.000000000000       1.256142548900       0.888226914500
 Fe      -1.256142548900       0.000000000000      -0.888226914500
 Fe       1.256142548900      -0.000000000000      -0.888226914500
  S      -1.845393493800       0.000000000000       1.304890253400
  S       1.845393493800      -0.000000000000       1.304890253400
  S      -0.000000000000      -1.845393493800      -1.304890253400
  S       0.000000000000       1.845393493800      -1.304890253400
END

Symmetry C(2v)

CHARGE 0.0 0.0

UNRESTRICTED

BASIS
type DZ
core Large
createoutput None
END

XC
GGA OPBE
END

eor