dftd4 FFI bindings

This project contains dftd4 FFI bindings, wrapper and build-from-source.

Current binding of dftd4: bb9bd94 (after )

Source code of dftd4 is available on github.

This crate is not official bindgen project. It is originally intended to potentially serve rust electronic structure toolkit REST.

Crate dftd4

This crate contains dftd4 FFI bindings and wrapper.

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API Document
FFI Binding	bb9bd94 after

Cargo features of dftd4

• d4s: Support of D4S dispersion model. Please note that this is not available in latest stable release of dftd4 (at the time writing this readme, is v3.7.0). Unless you build dftd4 from git repository, you may not use this feature (especially installed dftd4 from conda or similar).

Example: B97m with D4

For example, full code for computing B97m dispersion energy with D4:

fn main() {
    use dftd4::prelude::*;
    
    // atom indices
    let numbers = vec![1, 6, 6, 6, 6, 6, 6, 1, 1, 1, 1, 1, 35, 6, 9, 9, 9];
    // geometry in angstrom
    #[rustfmt::skip]
    let positions = vec![
        0.002144194,   0.361043475,   0.029799709,
        0.015020592,   0.274789738,   1.107648016,
        1.227632658,   0.296655040,   1.794629427,
        1.243958826,   0.183702791,   3.183703934,
        0.047958213,   0.048915002,   3.886484583,
       -1.165135654,   0.026954348,   3.200213281,
       -1.181832083,   0.139828643,   1.810376587,
        2.155807907,   0.399177037,   1.249441585,
        2.184979344,   0.198598553,   3.716170761,
        0.060934662,  -0.040672756,   4.964014252,
       -2.093220602,  -0.078628959,   3.745125056,
       -2.122845437,   0.123257119,   1.277645797,
       -0.268325907,  -3.194209024,   1.994458950,
        0.049999933,  -5.089197474,   1.929391171,
        0.078949601,  -5.512441335,   0.671851563,
        1.211983937,  -5.383996300,   2.498664481,
       -0.909987405,  -5.743747328,   2.570721738,
    ];
    // convert angstrom to bohr
    let positions = positions.iter().map(|&x| x / 0.52917721067).collect::<Vec<f64>>();
    // generate DFTD4 model
    let model = DFTD4Model::new(&numbers, &positions, None, None, None);
    // retrive the DFTD4 parameters
    let param = DFTD4Param::load_rational_damping("b97m", true);
    // obtain the dispersion energy and gradient, without sigma
    let (energy, gradient, _) = model.get_dispersion(&param, true).into();
    let gradient = gradient.unwrap();

    println!("Dispersion energy: {}", energy);
    let energy_ref = -0.025765015532807658;
    assert!((energy - energy_ref).abs() < 1e-9);
    println!("Dispersion gradient:");
    gradient.chunks(3).for_each(|chunk| println!("{:16.9?}", chunk));
}

Installation guide and Crate dftd4-src

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To use crate dftd4 in rust, you may need to perform some configuration to properly link libdftd4.so into your own program.

Install dftd4

Please refer to original github repository for more instructions.

The easiest way is install from conda/mamba, and you can retrive the shared/static library therein.

Manually link dftd4 into your project

Similar to other projects, after library search path properly defined

println!("cargo:rustc-link-search=native={}", path);

you may link dftd4 and mctc-lib, multicharge by cargo instructions in your own project:

// following code is for static linking
println!("cargo:rustc-link-lib=static=dftd4");
println!("cargo:rustc-link-lib=static=mctc-lib");
println!("cargo:rustc-link-lib=static=multicharge");
// following code is for dynamic linking
println!("cargo:rustc-link-lib=dftd4");
println!("cargo:rustc-link-lib=mctc-lib");
println!("cargo:rustc-link-lib=multicharge");

It should be noted that, for static linking, you may also need to dynamic link Fortran, OpenMP, BLAS, LAPACK libraries (for the library installed by conda or mamba, it is usually gfortran and gomp, blas, lapack).

Link dftd4 by crate dftd4-src

You can also link dftd4 by crate dftd4-src.

First, in your own project's lib.rs or main.rs, you need to add a line for explicitly importing this library:

extern crate dftd4_src;

If you have compiled dftd4 library, make sure path of it (together with mctc-lib) is either in

• DFTD4_DIR
• REST_EXT_DIR
• LD_LIBRARY_PATH
• or in other common system library paths.

If you have not compiled dftd4 library, you may try out cargo feature build_from_source, but that can also cause trobule when distributing your program binary, so use with caution.

Cargo features of dftd4-src

• build_from_source: This will use CMake and meson, and pull code from github to first perform build for dftd4. Though this option can be developer-friendly (you do not need to perform any other configurations to make program compile and run by cargo), build_from_source does not provide customized compilation.
• static: This will link static libary instead of dynamic one. Please note that 1. static linking may require additional Fortran and OpenMP linking, which is not provided in this crate; 2. staticly linking LGPL-3.0 license may require your project to be GPL-3.0.

License

This repository is licensed under LGPL-3.0, the same to dftd4.

Some parts of this project is derivative work of original library dftd4, and contains some source code (headers) and AI-translated code (pytest).