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HFPP - Hartree-Fock post-processing and SCLR

HFPP is a Fortran research code for post-processing a mean-field Hartree-Fock solution of a low-energy Hubbard model. It reads a localized/Wannier-basis model and the fixed-format outputs of a prior Hartree-Fock calculation, then evaluates Green-function and local-force-theorem quantities. Optional functionality includes exchange parameters, spin-wave dispersions, spin-orbit-coupling corrections, and self-consistent linear response (SCLR).

Main capabilities

  • Green-function contour integration with a rational Fermi-Dirac approximation.
  • Local-force exchange calculations and lf.dat output.
  • Curie-Weiss and optional spin-wave calculations.
  • SCLR response to spin-orbit coupling, including energy corrections and spin/orbital moments.
  • Optional Dzyaloshinskii-Moriya interaction (DMI) calculation from three magnetization directions.

The program entry point is main.f90; the principal modules are green.f90, response.f90, perturb.f90, properties.f90, spinwav.f90, and dmi.f90.

Requirements and build

The checked-in Makefile is configured for Intel Fortran and Intel MKL:

make

It invokes ifort -mkl and uses LAPACK routines. The recipe does not pass an explicit -o hf.x flag, so the generated executable name is compiler- and platform-dependent. After building, run the executable actually produced by the compiler, or add an explicit output name in a local build configuration.

Input workflow

Run the program from a calculation directory containing the following fixed-name files.

Purpose Files
Control and structure gflr.in, struct.in
Required Hartree-Fock outputs wav.out, eig.out, bond.out, pot.out, dens.out
Spin-wave data, when requested maglatt.in, bandpath.in
SCLR data sclr_ham.in, sclr_hamso.in, sclr_u.in; or sclr_vso.in in the alternative SOC-input mode; sclr_l.in is needed for orbital moments

gflr.in is positional. After its heading, it specifies the pole count, contour-point count, Hubbard-site spin, Fermi-Dirac temperature, electron count, exchange and spin-wave flags, then the SCLR flags/options and magnetization angles. See the comments in parameter.f90 and the supplied example before changing it.

For the usual SCLR input mode (soctype = 'r'), the code obtains the external SOC perturbation from the difference between sclr_hamso.in and sclr_ham.in. In the alternative mode (soctype = 'f'), it reads sclr_vso.in directly.

Typical sequence

  1. Run MFHF to generate wav.out, eig.out, bond.out, pot.out, and dens.out.
  2. Supply an equivalent struct.in and prepare gflr.in plus the desired exchange or SCLR inputs.
  3. Run the executable from that directory and inspect gf.out.
  4. For SCLR, an initial run with no sclr_r.out writes the response tensor. Run again to read that tensor and calculate the SCLR results.
  5. For DMI, perform the required calculations for the x, y, and z magnetization directions; the resulting forces_x.dat, forces_y.dat, and forces_z.dat are combined into dmi.dat.

Outputs

Calculation Main outputs
Diagnostics gf.out, poles.dat, separation.dat, frac.dat, error.dat, path.dat
Exchange and spin waves lf.dat, spinwav.dat
SCLR sclr_r.out, sclr.out
DMI forces_x.dat, forces_y.dat, forces_z.dat, dmi.dat

Results are written with replacement semantics. Use a separate working directory or preserve outputs before re-running a calculation.

Example

Example/NaFePO contains an SCLR input template for NaFePO. It is not a standalone runnable example: it does not include the required Hartree-Fock output files. In addition, the current code unconditionally reads lf.dat for the Curie-Weiss calculation, so an exchange-enabled run or a compatible pre-existing lf.dat is required even though the supplied gflr.in sets lexch = .false..

Scientific background

  1. I. V. Solovyev, "Combining DFT and many-body methods to understand correlated materials", Journal of Physics: Condensed Matter 20, 293201 (2008). https://doi.org/10.1088/0953-8984/20/29/293201
  2. I. V. Solovyev, "Self-consistent linear response for the spin-orbit interaction related properties", Physical Review B 90, 024417 (2014). https://doi.org/10.1103/PhysRevB.90.024417

License

This project is distributed under the MIT License.

About

Post Processing for Mean-Field Hartree-Fock. Applies the local force theorem and the Self-Consistent Linear Response theory to obtain parameters of spin hamiltonians.

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