MFHF - Mean-field Hartree-Fock solver

MFHF is a Fortran research code for solving low-energy Hubbard-type models in the self-consistent mean-field Hartree-Fock approximation. It starts from a localized/Wannier-basis Hamiltonian and local Coulomb interactions prepared from a prior DFT calculation (Quantum-Espresso + Wannier90 workflow). The solver produces the electronic structure, density matrices, and Hartree-Fock potentials used by the companion HFPP post-processing code.

Features

• Self-consistent Hartree-Fock solution of a low-energy Hubbard model.
• Wannier-basis hopping Hamiltonian and a local four-index Coulomb interaction matrix.
• Collinear calculations and a spin-orbit branch controlled by spinorb in hf.in.
• Explicit Coulomb matrices or spherical interaction parameterization.
• Optional density-of-states and band-structure output.

The program entry point is main.f90. Input/model handling is in parameters.f90; the Hartree-Fock Hamiltonian, density, energy, and plotting routines are in hamiltonian.f90, density.f90, energy.f90, and plot.f90.

Requirements and build

The supplied Makefile is configured for Intel Fortran and Intel MKL:

make

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

Inputs and running

The executable reads fixed filenames from its current working directory. Start from a copy of Examples/NaFePO4/ or create a separate calculation directory containing the required inputs.

File	Role
hf.in	Positional calculation controls
hf_struct.in	Lattice vectors and site positions
hf_kpt.in	k-point mesh/list
hf_ham.in	Wannier-basis hopping Hamiltonian
hf_mag.in	Initial magnetic/density-matrix data
hf_coulomb.in	Local Coulomb matrix; required when lsph = .false.
hf_soc.in	Spin-orbit input when required by the selected SOC mode
hf_path.in	Band path when bandplot = .true.

After the ignored heading line, hf.in gives the following values in order: spinorb, soctype, bondcoord, nelec, nscf, nener, etemp, ediff, mix, dosplot, smear, bandplot, and lsph. The provided NaFePO4 example is the best reference for the expected fixed-format inputs.

Run the built executable from that calculation directory. Output files are written with replacement semantics, so preserve results or use a new directory before re-running.

Outputs

MFHF always writes:

• hf.out - self-consistency log, energy, occupations, and magnetization.
• eig.out and wav.out - eigenvalues/Fermi energy and eigenvectors.
• bond.out - real-space bond information.
• pot.out and dens.out - converged Hartree-Fock potential and density matrix.

These files form the main interface to HFPP. Depending on the requested calculation, MFHF can also write dos.out, eigpath.out, wavpath.out, bands.1.out, bands.2.out, or bands.out. Density-of-states output is not implemented for spinorb = .true. in the current code.

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.