An open source, GPU enabled, *ab initio* and density functional
theory program developed by Götz lab at University of California San Diego and Merz
lab at Michigan State University.

## Features

- Hartree-Fock energy calculations
- Density functional theory calculations (LDA, GGA and Hybrid-GGA functionals available)
- Gradient and geometry optimization calculations (in-house and DL-FIND optimizers available)
- Mulliken charge analysis
- Exports Molden format for visualization of geometry and orbital data
- Supports QM/MM calculations with Amber22
- Fortran API to use QUICK as QM energy and force engine
- MPI parallelization for CPU platforms
- Massively parallel GPU implementation via CUDA for Nvidia GPUs
- Multi-GPU support via MPI + CUDA, also across multiple compute nodes

## Limitations

- Supports energy/gradient calculations with basis functions up to d
- Supports only Cartesian basis functions (no spherical harmonics)
- Effective core potentials (ECPs) are not supported
- DFT calculations are performed exclusively using SG1 grid system

## Installation

Supported platforms: Linux

## Getting Started

## Known Issues

A list of installation and runtime issues can be found here.

## Citation

Please cite QUICK-22.03 as follows.

Manathunga, M.; Shajan, A.; Giese, T. J.; Cruzeiro, V. W. D.; Smith, J.; Miao, Y.; He, X.; Ayers, K; Brothers, E.; Götz, A. W.; Merz, K. M. QUICK-22.03 University of California San Diego, CA and Michigan State University, East Lansing, MI, 2022.

If you perform density functional theory calculations please also cite:

Manathunga, M.; Miao, Y.; Mu, D.; Götz, A. W.; Merz, K. M.
Parallel Implementation of Density Functional Theory Methods in the Quantum Interaction Computational Kernel Program.
*J. Chem. Theory Comput.* 16, 4315-4326 (2020).

and in addition for any XC functional except B3LYP:

Lehtola, S.; Steigemann, C.; Oliveira, M. J. T.; Marques, M. A. L.
Recent developments in Libxc - A comprehensive library of functionals for density functional theory.
*Software X* 7, 1 (2018)

If you use the GPU version please also cite:

Miao, Y.; Merz, K. M.
Acceleration of High Angular Momentum Electron Repulsion Integrals and Integral Derivatives on Graphics Processing Units.
*J. Chem. Theory Comput.* 11, 1449–1462 (2015).

and for multi-GPU calculations please also cite:

Manathunga, M.; Jin, C; Cruzeiro, V. W. D.; Miao, Y.; Mu, D.; Arumugam, K.; Keipert, K.; Aktulga, H. M.; Merz, K. M.; Götz, A. W.
Harnessing the Power of Multi-GPU Acceleration into the Quantum Interaction Computational Kernel Program.
*J. Chem. Theory Comput.* 17, 3955–3966 (2021).

If you use QUICK in QM/MM simulations please cite:

Cruzeiro, V. W. D.; Manathunga, M.; Merz,K. M.; Götz, A. W.
Open-Source Multi-GPU-Accelerated QM/MM Simulations with AMBER and QUICK.
*J. Chem. Inf. Model.* 61, 2109–2115 (2021).

If you perform geometry optimization calculations using DL-FIND optimizer please also cite:

Kästner, J.; Carr, J. M.; Keal, T. W.; Thiel, W.; Wander, A.; Sherwood, P. DL-FIND: An Open-Source Geometry Optimizer for Atomistic Simulations.
*J. Phys. Chem. A* 113, 11856-11865 (2009).

## License

QUICK is licensed under Mozilla Public License 2.0. More information can be found here.

## Special Note to Users

QUICK is still in the experimental stage and we do not guarantee it will work flawlessly in all your applications. But we are working hard to detect and fix issues. If you experience any compile or runtime issues, please report to us through issues section of this repository.