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Applications of First Principles Calculations
The application of first principles electronic structure calculations involves solving the Schrödinger equation for manyelectron systems to analyze various substances and calculate physical quantities. When dealing with electronic systems, it is often simply referred to as "first principles calculations." The term "first principles electronic structure calculations" or "first principles calculations" specifically refers, in a narrow sense, to calculations imposed with periodic boundary conditions, such as in the case of crystalline solids, surfaces, and interfaces. In the field of chemistry, calculations for molecules under isolated boundary conditions are generally termed "ab initio calculations."
However, in this article, both are broadly referred to as "first principles calculations."
First principles calculations are widely used in industrial research and development. Literally executing the approach of "solving the Schrödinger equation for manyelectron systems" is almost impossible in practical terms, so first principles calculations based on density functional theory (DFT) are realistically performed. As there is already a wealth of information on the basics of DFT, it will be omitted here.
While the foundational theory of DFT remains an advanced research topic, actual applied calculations using package software such as OpenMX, Quantum ESPRESSO, VASP, and GAUSSIAN are active. DFT serves as a pragmatic simulation tool and has a very broad range of applications, making it applicable to almost anything in materials science.
Below is a list of physical properties and analyzable phenomena (in part) that can be obtained through DFTbased first principles calculations, which are deemed useful in various fields. It is hoped that this provides hints on the versatility of DFT in addressing diverse aspects of materials science.
INTRODUCTION
The physical properties and analyzable phenomena obtained through firstprinciples calculations based on DFT
LIST
【OTHERS】
Wannier Function
Berry Curvature
Churn Number
【NANOMATERIALS/LOWDIMENSIONAL MATERIALS/MOLECULAR SCIENCE】
Atomic Structure
Electronic Structure (Density of States, Energy Levels)
Optical Response
Electrical Conductivity
Excitation Energy
【EARTH/SPACE】
Crystal Structure under high Pressure Environment inside a Planet
【MEASUREMENT】
XRD
XPS
XANES
EELS
Infrared Spectroscopy
Raman Spectroscopy
ARPES
STM
AFM
NMR
【MAGNETIC MATERIALS/SPINTRONICS】
Magnetic Moment/Saturation Magnetization
Magnetic Anisotropy Energy
Magnetic Structure (Ferromagnetism, Antiferromagnetism, Noncollinear Magnetism)
Exchange Coupling Constant
【DRUG DISCOVERY】
Molecular Structure
Binding Energy
【LIVING THING】
Proton Transport
Enzymatic Reaction
【Optical Materials/Lasers】
Complex Dielectric Function (Reflectance, Refractive Index, Absorption)
Nonlinear Optical Constant
Strong Laser Field Response (Higher Harmonics, Dielectric Breakdown, Realtime Electron Dynamics)
【CERAMICS】
Elastic Constant
Polarization (Ferroelectricity)
Piezoelectric Constant
【BATTERY】
Equilibrium Potential
Interface Structure
Ionic Conduction (Diffusion Coefficient)
【THERMOELECTRIC】
Seebeck Coefficient
【SUPERCONDUCTOR】
Transition Temperature
【METAL】
Cohesive Energy
Embrittlement
【CATALYST】
Surface, Molecular Adsorption (Structure, Energy)
Reaction Barrier/Chemical Reaction Rate
Diffusion Barrier
【HIGH MOLECULAR】
Monomer Physical Properties
Reaction Barrier
【SEMICONDUCTOR】
Electronic Band Structure（Band Gap,Effective Mass）
Electronic Density of States
Permittivity
Point Defects (Formation Energy, Defect Levels, Hyperfine Structure Constants)
Surface/Interface Structure (Epitaxial Growth)
Work Function
Electron Affinity
In addition, there are several useful calculations across various fields. For example, calculations of the total energy (internal energy) of a system, phonons, or thermodynamic quantities (free energy, enthalpy, etc.) using firstprinciples molecular dynamics methods. Similarly, information such as electron density distribution, oneelectron wave functions such as molecular orbitals and Bloch orbitals, and atomic charges per atom, becomes crucial for obtaining a microscopic understanding of phenomena.
In recent years, there has been an increasing importance of tools that generate necessary training data for machine learning of atomic potentials (force fields) used in classical molecular dynamics methods or for materials informatics. These tools play a significant role in the generation of data needed for machine learning and materials informatics related to atomic potentials (force fields) used in classical molecular dynamics methods.
OTHERS
Our material calculation platform, Quloud, developed by our company, offers three firstprinciples calculation software options:

RSDFT

OpenMX

Quantum ESPRESSO
These three software options cover a significant portion of the calculations mentioned above. Moreover, Quloud supports a graphical user interface for key calculation functionalities. Additionally, we provide a service where our researchers can handle the calculations on behalf of the customers. The environment is designed to allow beginners to start material simulations with confidence. Therefore, please feel free to inquire, starting from questions like "Can you perform this type of calculation?" We would be delighted to assist you.
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