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©2019 Entos Inc

Quantum Simulation for Real-World Problems

entos is a software package that enables ab initio molecular dynamics calculations on molecular and condensed-phase chemical reactions and other processes. entos focuses on multiscale embedding methods that allow for accurate simulation of a small, chemically important region, in a larger, complex chemical environment.

 

entos is designed for ab initio MD simulations of molecular and condensed-phase chemical reactions and other processes, with particular focus on mean-field and quantum embedding methods for electronic structure. The entos software package is developed in the C++14 programming language with a structure that enables flexibility (by providing a long-term sustainable platform for development of methods in this area), efficiency (via task-based multi-threaded parallelism), and rigorous software engineering standards.

entos is a software package that enables ab initio molecular dynamics calculations on molecular and condensed-phase chemical reactions and other processes. entos focuses on multiscale embedding methods that allow for accurate simulation of a small, chemically important region, in a larger, complex chemical environment.

 

Key features include efficient implementations of density-functional theory (DFT), density-corrected DFT, embedded mean-field theory (EMFT), and Grimme’s semi-empirical tight-binding method GFN-xTB.

For all of these methods, energy, gradient and semi-analytic Hessian calculations are available, enabling full geometry optimizations, constrained geometry optimizations, transition-state optimizations, and thermochemical analysis. For DFT and EMFT, excited-state calculations are possible through linear response and SCF. All methods support calculations on fractional particle number and fractional spin systems.

 

QM/MM calculations are made possible via combination with external molecular dynamics packages. Classical and quantized molecular dynamics simulations (via ring-polymer molecular dynamics) can be performed with any available energy method.

entos is developed in the C++14 programming language with a clear and well-designed structure. The design aims included flexibility (in the sense of providing a long-term sustainable platform for development of methods in this area), efficiency (which is realized through a task-based parallelism model), and software engineering standards geared towards industrial use. Parallelism is achieved using the Intel Threaded Building Blocks library.

The code has been developed using modern software engineering best practices, including version control, unit testing, test coverage analysis, and continuous integration.

entos uses the following libraries, and the contributions made by the developers of them are gratefully acknowledged:

  • libecpint for ECP integrals, by Rob Shaw
     

  • libxc for exchange-correlation functionals, Miguel Marques, Micael Oliveira, and Susi Lehtola, see also Software X7, 1 (2018) and Comput. Phys. Commun., 183, 2272 (2012) 
     

  • Armadillo for linear algebra

We are also making a number of widely reusable components developed in our own groups available through open-source licenses:

 

  • intception for generated molecular integrals, by James Womack 
     

  • libirc for transformation to internal redundant coordinates, by Rocco Meli

  • MOB-ML features for quantum machine learning, by Sherry Cheng and Matt Welborn