Fractional Charge Density Functional Theory (FC-DFT)

FC-DFT is a Python package for DFT calculations at electrochemical interfaces. It combines the wide-band limit (WBL) approximation for electrode coupling with continuum solvation models to study molecules at electrode/solvent interfaces under applied potential.

The code computes single-point energies, optimized structures, vibrational frequencies, and solvation free energies of open quantum systems using FC-DFT methodology.

Requirements

• GeomeTRIC
• PySCF
• PyAMG
• PyAMGCL
• GPU4PySCF (optional for GPU-accelerated PBE solver)
• AMGX (optional for GPU-accelerated PBE solver)

Installation

• Option 1: Install stable release via PyPI:

  pip install fcdft
  

• Option 2: Clone the repository:

  git clone https://github.com/Yang-Laboratory/FC-DFT.git
  cd FC-DFT
  pip install .
  

• (Deprecated) Once one of the options is completed, change directory to:

  $PYTHONPATH/fcdft/lib
  

• (Deprecated) Create build directory and go into it:

  mkdir build && cd build
  

• (Deprecated) Compile C libraries:

  cmake .. && make
  

Tips for compilation

• When linking Intel MKL, make sure to link the sequential one by cmake -DBLA_VENDOR=Intel10_64lp_seq ... The performance of Intel MKL over OpenBLAS has not been tested. One may want to link OpenBLAS instead by cmake -DBLA_VENDOR=OpenBLAS .. for easier installation.
• If CMake fails to find either lapacke.h or cblas.h, set C_INCLUDE_PATH manually.

Features

• FC-DFT calculations for all density functional approximations supported by PySCF.
• Wide-band limit calculations, namely WBL-Molecule.
• Non-linear Poisson-Boltzmann solver in real space and its analytic nuclear gradients.
• Numerical Hessian calculations.

Notes

Poisson-Boltzmann geometry optimization uses RESP atomic charges, which are computed by the code provided by https://github.com/swillow/pyscf_esp after some modifications for computational efficiency.

How to Cite

Please cite the paper below if this code was directly or indirectly helpful to your research.

Jun-Hyeong Kim, Dongju Kim, Weitao Yang, and Mu-Hyun Baik. Fractional Charge Density Functional Theory and Its Application to the Electro-inductive Effect. J. Phys. Chem. Lett. 2023, 14, 3329-3334

Jun-Hyeong Kim and Weitao Yang. Fractional Charge Density Functional Theory Elucidates Electro-Inductive and Electric Field Effects at Electrochemical Interfaces. Submitted ChemRxiv: 10.26434/chemrxiv-2025-6qqfb

Bug Report and Feature Request

Please open a thread on the Issues tab.