QuantumATK: An integrated platform of electronic and atomic-scale modelling tools (1905.02794v2)

Abstract: QuantumATK is an integrated set of atomic-scale modelling tools developed since 2003 by professional software engineers in collaboration with academic researchers. While different aspects and individual modules of the platform have been previously presented, the purpose of this paper is to give a general overview of the platform. The QuantumATK simulation engines enable electronic-structure calculations using density functional theory or tight-binding model Hamiltonians, and also offers bonded or reactive empirical force fields in many different parametrizations. Density functional theory is implemented using either a plane-wave basis or expansion of electronic states in a linear combination of atomic orbitals. The platform includes a long list of advanced modules, including Green's-function methods for electron transport simulations and surface calculations, first-principles electron-phonon and electron-photon couplings, simulation of atomic-scale heat transport, ion dynamics, spintronics, optical properties of materials, static polarization, and more. Seamless integration of the different simulation engines into a common platform allows for easy combination of different simulation methods into complex workflows. Besides giving a general overview and presenting a number of implementation details not previously published, we also present four different application examples. These are calculations of the phonon-limited mobility of Cu, Ag and Au, electron transport in a gated 2D device, multi-model simulation of lithium ion drift through a battery cathode in an external electric field, and electronic-structure calculations of the composition-dependent band gap of SiGe alloys.

• The paper introduces QuantumATK as an integrated platform combining DFT, semi-empirical, and classical force-field methods for versatile materials modeling.
• The paper demonstrates robust computational engines, including NEGF for quantum transport and reliable calculations of phonon-limited mobility and magnetic anisotropy energy.
• The paper highlights QuantumATK’s capability to bridge atomic-level simulations with device-scale applications, advancing research in nanotechnology and electronics.

QuantumATK: A Comprehensive Platform for Electronic and Atomic-Scale Modeling

The paper "QuantumATK: An Integrated Platform of Electronic and Atomic-Scale Modeling Tools" provides an in-depth exploration of the QuantumATK software package, which is designed for simulating electronic and atomic-scale systems through various computational methods. Developed since 2003, this platform integrates multiple simulation engines, including Density Functional Theory (DFT), Semi-Empirical (SE) methods, and Classical Force Fields (FF). The paper offers a detailed account of the platform’s capabilities, its internal structure, and its application across different fields in materials science.

Overview of QuantumATK

QuantumATK stands out for its integration of several computational engines. These engines support a wide range of methods from wave-function based quantum mechanical approaches to classical atomistic models. The main engines include ATK-LCAO and ATK-PlaneWave for DFT calculations, ATK-SE for semi-empirical calculations, and ATK-ForceField for molecular dynamics simulations using classical potentials. This variety allows researchers to select the methodology best suited to their problem, whether it requires high accuracy or large-scale simulations.

Computational Engines and Techniques

1. Density Functional Theory (DFT): QuantumATK implements DFT using both localized and plane-wave basis sets, allowing for flexibility depending on the system size and computational resources. The software provides tools for ground-state calculations, band structure analysis, and quantum transport simulations via the Non-equilibrium Green's Function (NEGF) method.
2. Semi-Empirical Methods: These methods provide a computationally efficient alternative to DFT by using parameters fitted to empirical data. QuantumATK offers several models, including orthogonal and non-orthogonal tight-binding Hamiltonians, suitable for both small and large systems.
3. Classical Force Fields: The ATK-ForceField engine supports various force fields, such as Lennard-Jones and more complex many-body potentials, enabling large-scale molecular dynamics simulations. This is crucial for studying thermodynamic properties and phase transitions in materials.

Methodological Innovations and Results

The paper highlights several novel modules integrated within QuantumATK that enhance its capability to handle complex simulations. These include modules for calculating phonon properties, electron-phonon coupling, and transport coefficients, all critical for evaluating materials’ potential as conductors or thermoelectric materials.

Key Numerical Results

• Phonon-Limited Mobility: The paper effectively demonstrates the computation of phonon-limited resistivity in metals such as Cu, Ag, and Au. Such results are pivotal for understanding electron transport properties in nanoscale materials, emphasizing the software's ability to handle detailed electron-phonon interaction calculations.
• Magnetic Anisotropy Energy: The calculation of magnetic anisotropy energy (MAE) using QuantumATK's force theorem method provides reliable results comparable to other advanced methods, showcasing the tool's broad applicability in magnetic material research.
• Quantum Transport Simulations: The integration of transport studies using NEGF within the framework allows for realistic modeling of devices such as field-effect transistors, enhancing the platform's utility in semiconductor research.

Implications and Future Directions

QuantumATK's comprehensive integration of multi-scale and multi-physics simulations addresses a significant need in both academic and industrial research environments. The platform facilitates the transition from material property prediction at the atomic level to the simulation of devices, bridging the gap between quantum mechanical simulations and practical applications in technology design, such as in electronics and energy materials.

Future advancements in QuantumATK are likely to focus on enhancing parallel computing capabilities, improving algorithm efficiency, and expanding the range of materials databases for empirical models. These aspirations are critical for meeting the growing complexity of materials science problems as researchers pursue new frontiers in nanotechnology and quantum materials.

Conclusion

QuantumATK provides a versatile and powerful software suite for researchers in electronic and atomic-scale modeling. By integrating a wide array of computational strategies within one platform, it enables state-of-the-art simulations across diverse scientific and engineering disciplines. The detailed examination of its methods, capabilities, and applications in this paper underscores QuantumATK’s role in advancing materials modeling and its potential for future developments in computational materials science.