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README.md

INQ

Xavier Andrade (LLNL), Alfredo A. Correa (LLNL)

INQ is an engine for electronic structure calculations. It can work in three ways, as a standalone electronic structure code, as a library to implement complex electronic structure methods, or a proxy-app to evaluate the performance of electronic structure algorithms in high-performance computing platforms. It concentrates on algorithms as a portability hardware layer, generic types and flexibility of usage.

INQ is based on density functional theory (DFT). It can calculate ground state properties in DFT, and also excited states using time-dependent DFT (TDDFT) in real-time and linear-response. It implements different approximations for the exchange and correlation part: semi-local functionals like LDAs, GGAs and metaGGAs, and hybrid functionals that are implemented through the ACE approach for fast execution.

One key feature of INQ is that is designed from the ground up to work in modern high-performance computing platforms. It has support for GPU parallelization (through different frameworks), thread parallelization and distributed memory parallelization using MPI (and Nvidia NCCL). The thread parallelization is designed so that different tasks whithin the DFT approach are performed simultaneously, this achieves better scalability with respect to data parallelization alone. INQ can perform calculations with unpolarized, polarized and non-colinear spin.

INQ attempts to be as agnostic as possible with the representation used for the states and other quantities that appear in DFT. It uses plane waves by default, but other representations like real space will be available.

In order to keep the code simple, INQ is designed as modular as possible, it uses libraries for most of the operations that can be done independently. Some libraries, like pseudopod (for pseudopotential parsing) or multi (for multidimensional arrays) are developed by INQ authors. Other are written by third parties, like libxc (for exchange correlation functionals). In the future, some other parts of INQ might be split into independent library.

This is a list of libraries INQ depends on:

  • boost-multi: for multidimensional arrays (developed by A. A. Correa)
  • pseudopod: for pseudopotential parsing (developed X. Andrade)
  • boost-mpi3: for distributed memory parallelization (developed by A. A. Correa)
  • libxc: for exchange correlation functionals (X. Andrade is a contributor)
  • cuda: for GPU parallelization
  • pcg-cpp: for random number generation
  • catch2: for unit testing and validation
  • blas/lapack: for linear algebra
  • slate: for parallel linear algebra (work in progress)
  • spglib: for symmetries and k-point generation (work in progress)

INQ is work in progress, some of the features are not well tested or are not available at the moment.

Components

  • Electronic states, complex and real fields
  • Solvers
  • Diagonalization
  • CPU/GPU generic algorithms
  • Parallel distribution MPI/GPU/threads

Basic installation

sudo apt install libblas-dev liblapack-dev libfftw3-dev

Instructions for compiling with Cuda

git clone ...
cd inq
autoreconf -i
cd your_build
export CXX="/usr/lib/cuda/bin/nvcc -x cu"
export CXXFLAGS="-D_DISABLE_CUDA_SLOW -O3 -std=c++14 --expt-relaxed-constexpr --compiler-options -std=c++14,-Wall,-Wfatal-errors"
export CXXLD=/usr/lib/cuda/bin/nvcc
../../inq/configure -prefix=$HOME --enable-cuda --with-cuda-prefix

This instructions might be incomplete, to see how to have a basic install in a standard distribution see .gitlab-ci.yml.

Release information

INQ is licensed under the terms of the LGPL v3 License.

LLNL-CODE-803817

CP Number: CP02279 Software Title: Electronic Structure Engine Date Submitted: Wednesday, December 11, 2019 Date Accepted: Wednesday, January 29, 2020

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The work was supported by the U.S. Department of Energy, Office of Science, Materials Sciences and Engineering Division.

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