Materials & AI · glossary
Met an unfamiliar term while reading? Start with the concept.
62 terms
See allThe examples explain the concept. For actual research results, see AI in materials에서 원문과 함께 확인하세요. 엄선한 용어 86개에는 Colab에서 바로 돌려볼 수 있는 실습 노트북이 있습니다. “AI 자동 추가” 표시가 붙은 용어는 새 이슈를 수집할 때 자동으로 추가된 것으로, 아직 사람이 검토하지 않았고 실습 노트북이 없습니다. 노트북의 데이터는 개념 확인용으로 생성한 값이며 실제 측정값이 아닙니다.
Crystal Structure
The periodic spatial arrangement of atoms. The same composition can behave differently depending on the arrangement.
Comparing different structures made of the same elements.
Density Functional Theory · DFT
A quantum-mechanical method that computes the electronic structure and the energy of matter through the electron density.
Computing the energy of candidate crystals to compare their stability.
Formation Energy
The energy of a substance measured against the energies of its constituent elements in their reference states.
A negative value still leaves room for decomposition into other compounds being more favourable.
Energy Above Hull · E_hull · 볼록껍질
How much higher in energy a phase sits than the most stable combination of phases at the same composition.
Looking first at candidates near zero, without treating that as the same thing as being synthesisable.
Band Gap · 띠틈
The energy difference between the top of the valence band and the bottom of the conduction band.
Used as the figure of merit when comparing semiconductor candidates.
Space Group · 대칭성
The classification of a crystal’s spatial symmetry, including translation and rotation.
Sorting crystal structures by their symmetry.
Molecular Dynamics · MD
A simulation that integrates the equations of motion under the forces on the atoms to study structure and transport.
Following atomic diffusion over time at different temperatures.
Phase Diagram · CALPHAD · 상평형
A map of which phase is stable against composition, temperature and pressure, and the thermodynamic modelling that computes it.
Checking which phase forms first at a given alloy composition.
X-ray Diffraction · XRD · 회절 패턴
An analysis that identifies phases and structures from the positions and intensities of diffraction set by the spacing of crystal planes.
Comparing a measured pattern with computed ones to decide which phase formed.
Microstructure · 결정립 · Grain
The structure at microscope scale — grains, phase distribution and defects — which acts directly on the properties.
Measuring the grain size distribution from an image and relating it to strength.
Topology
The property and classification in which structure or connectivity is preserved under continuous deformation. In materials, it is used to distinguish different structural types by comparing the network connectivity of atoms, rings, and channels.
In a porous framework, even with the same composition, different topology can lead to completely different properties.
Defect Topology
It is a structural property that indicates how defects are spatially connected and arranged. It is useful for explaining how not only the simple number of defects but also the connectivity and geometry affect material properties.
The defect topology of oxygen vacancies can change charge trapping behavior.
Nonadiabatic Molecular Dynamics
It is a molecular dynamics method in which electronic state transitions and atomic nucleus motion occur together. Because it treats the coupled dynamics of electrons and nuclei, it is used to simulate excited-state processes and charge transfer.
Carrier recombination pathways in photoexcited oxides can be tracked with Nonadiabatic Molecular Dynamics.
topological visibility
A concept that indicates how clearly topological features appear in observable data signals. If the signal is blurred by noise or temperature effects, topological visibility can be considered low.
In nanowire conductance, the higher the topological visibility, the easier it is to identify Majorana features.
Charge Density
A physical quantity that indicates how charge is distributed at each position in space. In electronic structure calculations, it is a key result that describes the spatial distribution of electrons.
By learning the charge density obtained from DFT, it is possible to rapidly estimate the electronic structure properties of materials.
Conformational Ensemble
A concept in which a molecule or polymer exists not as a single fixed structure but as a collection of multiple possible structural states. The occupancy or distribution of each structure is considered together.
When predicting the structure of a disordered protein, a conformational ensemble is generated instead of a single structure.
Site Heterogeneity
A phenomenon in which structure, composition, electronic state, and reactivity differ depending on location within the same material or surface. Because of differences in the local environment, variations arise that cannot be explained by the overall average alone.
In nanoparticle catalysts, the reaction differences among different active sites are interpreted as Site Heterogeneity.
Preparation Procedure Information Extraction
The task of automatically finding information corresponding to experimental preparation procedures in literature or reports and extracting it in a structured form. In materials research, it is used to organize reproducibility-critical information such as reagents, sequence, and conditions into a machine-readable format.
From the body text of a paper, the mixing order of the solution and the heat-treatment conditions are extracted to create an experimental protocol database.
Surface-Enhanced Raman Scattering · SERS
A phenomenon in which the Raman scattering signal is greatly amplified at the surface of a metal nanostructure. It is widely used in spectroscopic sensors because trace molecules can be detected rapidly.
In materials sensors, SERS is used to detect low concentrations of contaminants or biomarkers.
Real-space Representation
A method of directly expressing physical quantities such as wavefunctions or electron density in spatial coordinates. It represents states with a focus on position dependence rather than reciprocal space or basis-function coefficients.
Real-space Representation is used in wavefunction approximations that directly handle the electron distribution around atoms.
Electron Tomography
An imaging technique that reconstructs the three-dimensional structure of a sample by using projection images acquired from multiple angles in an electron microscope. It is widely used to obtain atomic-scale structural information.
The three-dimensional atomic arrangement of a nanomaterial can be reconstructed by Electron Tomography and then corrected with AI.
Volatile Organic Compound · VOC
A collective term for organic compounds that easily vaporize at room temperature. They are often major sources of odor, air pollution, and sensor response.
In indoor air quality measurement, a sensor estimates the concentration of a specific volatile organic compound.
Electronic Nose
A system that distinguishes composite signal patterns produced by gases or volatile substances using a sensor array and a pattern-recognition algorithm. Rather than measuring odor directly, it identifies targets by learning combinations of responses from multiple sensors.
An electronic nose is used when classifying volatile organic compound types from the response pattern of a gas sensor array.
Liquid-Liquid Phase Diagram
A phase diagram that shows how phase separation appears in two liquid phases or a liquid mixture as a function of composition, temperature, and pressure. The phase boundary and phase-separation region make it possible to understand the behavior of the mixture.
In an extraction process, the Liquid-Liquid Phase Diagram is used to find the composition range in which separation proceeds well.
onsite interaction · on-site interaction
It denotes the interaction strength acting between two particles at the same site, and it is a key parameter of the Hubbard model. It determines the strength of electron correlation and the energy cost of an occupied state.
In a qubit array model, the onsite interaction strength can be inversely estimated from data.
onsite energy · on-site energy
In a lattice model, it is the local energy term when an electron exists at each site. It can vary with the surrounding potential, impurities, compositional fluctuations, and gate voltage.
In a semiconductor quantum dot array, site-to-site deviations in onsite energy can be estimated.
Hubbard model
It is a lattice model of strongly interacting electron systems that simply describes the hopping and local interactions between electrons. It is widely used to explain problems such as strongly correlated electron systems, magnetism, Mott insulators, and quantum dot arrays.
In charge stability analysis of a quantum dot qubit array, Hubbard model parameters can be estimated.
Constant Potential
In an electrochemical system, this refers to a condition in which the electrode potential is maintained at a constant value. It is important when treating systems in which the charge distribution and surface reaction barriers vary with potential.
The surface adsorption energy and reaction barrier are calculated under constant potential conditions.
Passivation
Passivation is the process of reducing surface defects, reactive sites, and charge traps to improve the chemical and electrical stability of a material. It can be implemented through methods such as coating, adsorption, and surface treatment.
In perovskite solar cells, interfacial passivation reduces recombination and improves efficiency and stability.
Potential Energy Surface · PES
A functional landscape that shows how the energy of a system changes with atomic arrangement or structural coordinates. It is fundamental for understanding phenomena such as reaction pathways, stable structures, and diffusion.
The change in energy according to the relative sliding position of the bilayer is represented by a PES to examine stacking stability.
Heterogeneous Formulation
A formulation in which different components, phases, particles, or additives are mixed non-uniformly. Because the composition or structure varies spatially, the properties can also vary depending on location.
In a composite coating, if particle dispersion is not uniform, the resulting heterogeneous formulation can lead to large property variations.
Kinetic Stability
A property in which a structure remains maintained for a long time under actual conditions because the barrier for structural transformation is large, even if it is not the thermodynamically most stable state. It is important when judging synthetic accessibility and the possibility of actual existence.
The candidate magnetic structure is checked to see whether it is kinetically stable in calculation.
Atomistic Simulation
A computational method that models the structure and properties of materials based on interactions at the atomic level. Molecular dynamics, Monte Carlo, and interatomic potential calculations belong to this category.
The phase stability of an oxide with an interface is compared using atomistic simulation.
Additive Manufacturing · AM · 3D Printing
A manufacturing method that builds a desired shape and internal structure by stacking material layer by layer. It allows comparatively free design of the process path and local structure.
Pore structure and conductive distribution in aerogels or composites are controlled by additive manufacturing.
Quantum Modelling
A modelling method that predicts material properties by describing the behavior of atoms and electrons in quantum-mechanical terms. It usually includes calculations such as density functional theory and deals with electronic structure and energy.
The binding characteristics of the passivation molecule can be evaluated by Quantum Modelling to narrow down candidates.
Field
A physical quantity defined at each position in space or spacetime. It is used when describing a continuous distribution such as temperature, potential, displacement, or an order parameter.
The order parameter field of the material microstructure can be predicted to analyze changes in the domain structure.
Adsorption Heat
This is the heat released or absorbed when a gas is adsorbed onto a surface. It is an important thermodynamic quantity that indicates the strength of the adsorption bond and the intensity of surface interactions.
Adsorption heat is used to evaluate how strongly hydrogen binds in MOF pores.
Adsorption Isotherm
This is a curve that shows the relationship between adsorption amount and pressure or concentration at a constant temperature. It is used to compare a material's storage capacity, surface affinity, and pore-filling behavior.
When comparing MOF hydrogen-storage candidates, adsorption isotherms at different temperatures are calculated.
Gas Adsorption
This is the phenomenon in which gas molecules adhere to and remain on a solid surface or inside pores. Adsorption is divided into physisorption and chemisorption, and it is strongly governed by the pore structure and surface properties of the material.
When evaluating the hydrogen-storage performance of porous MOF, gas adsorption isotherms are calculated.
High-throughput First-principles Search
A search method that rapidly screens candidate properties by applying first-principles calculations in bulk to many candidates. It uses automation and screening strategies together to reduce computational cost.
It quickly evaluates thousands of candidates in a magnetic composition space to identify promising compositions.
Spectroscopic Property
A spectroscopic property refers to measurable optical responses that appear when a material interacts with light, such as absorption, emission, and fluorescence lifetime. It can vary depending on the electronic structure, local coordination environment, and defect states.
In rare-earth-doped materials, spectroscopic property is used to predict emission spectra and lifetimes.
Tensor
A multidimensional physical quantity that generalizes scalars and vectors, and whose value can vary with direction. It is used to represent direction-dependent material properties such as stress, strain, and piezoelectric coefficients.
A piezoelectric tensor has different components depending on the crystal orientation, so it must be predicted in tensor form.
Substructure
A repeated or functionally meaningful partial structure within a larger molecule or polymer structure. It is used as a unit of description when the whole molecule is difficult to handle directly or when interpretability needs to be improved.
When evaluating polymer dielectric candidates, descriptors are generated for each substructure and used for screening.
Ferroelectric
A material that has spontaneous polarization even without an external electric field, and whose polarization direction can be changed by an electric field. It is widely used in non-volatile memory, sensors, and actuators.
The change in the polarization state of a Ferroelectric affects charge transport characteristics.
Carrier Dynamics
A concept that describes the generation, motion, scattering, and recombination processes of charge carriers, that is, electrons and holes, in semiconductors or insulators. It is central to understanding the electrical and optical responses of materials.
We analyze whether Carrier Dynamics change according to polarization changes through ultrafast simulations.
Nonadiabatic Dynamics
This deals with dynamics in a state where the motions of electrons and atomic nuclei are not separated and are strongly coupled to each other. It is especially used in processes where electronic state transitions are important, such as excited states or charge transfer.
After photoexcitation, the ultrafast charge transfer in the material is simulated with Nonadiabatic Dynamics.
Interatomic Potential
A function or model that approximately represents the interaction energy between atoms. It is used to rapidly calculate energy and forces from atomic structures.
In solid-liquid interface simulations, an interatomic potential is used to predict energy and forces.
Phonon
A quasiparticle formed by quantization of atomic vibrations in a crystal, and a fundamental concept for describing lattice thermal conductivity and heat transport. It is used when treating the collective behavior of vibrational modes.
When analyzing heat transfer at an alumina interface, phonon scattering and transmission are considered together.
Inelastic Scattering
A phenomenon in which a particle or quasiparticle exchanges energy with a material during interaction, so the energy before and after scattering differs. Because it is accompanied by energy loss or generation, it is important for interpreting spectroscopy and transport phenomena.
If phonons undergo inelastic scattering in interfacial heat transfer, the energy transfer pathway can change.
Effective Hamiltonian
An Effective Hamiltonian is a Hamiltonian that approximates a complex physical system with fewer degrees of freedom. It retains only the energy ranges or interactions of interest to simplify the calculation.
To quickly calculate the electronic dynamics of a photoexcited crystal, one can learn and use an Effective Hamiltonian.
magnetic diffuse scattering
An abnormal scattering signal that appears when magnetic order does not achieve complete long-range periodicity or when thermal fluctuations are present. It reflects specific spin correlations and short-range magnetic order.
In powder neutron diffraction, the magnetic diffuse scattering pattern can be used to back-calculate interaction parameters.
Transition State Search
A computational procedure for finding the saddle point with the highest energy along a chemical reaction pathway. It is essential for understanding reaction rates and activation barriers.
Transition State Search is performed to predict the rate of a surface catalytic reaction.
Elementary Reaction
An elementary reaction is a single fundamental reaction event that is not divided into multiple steps. Reaction networks and microkinetic models are constructed by collecting such elementary reactions.
Adsorption, surface diffusion, and bond formation are each treated as one elementary reaction.
Reaction Network
A reaction network is a system that represents the connection relationships among chemical reactions and species as a graph. Each node and edge expresses a possible reaction pathway and transition relationship.
In catalytic CO2 hydrogenation, the possible elementary reactions are gathered to construct the reaction network.
Vacancy Formation Energy
The energy required to remove one atom from a crystal and create a vacancy. It is used to gauge how easily defects form and the stability at high temperature.
In Ni-based superalloys, vacancy formation energy is predicted to compare diffusion behavior.
Strain Mapping
A map that spatially represents the strain distribution inside a specimen. It is used to quantify local lattice distortion and stress states.
In nanocrystalline TEM analysis, strain mapping is used to examine local strain around defects.
Phase Stability
It is the degree to which a given phase is thermodynamically more likely to be retained than other phases under specific temperature, pressure, and composition conditions. Higher phase stability makes it easier to maintain the desired crystal phase or microstructure.
When the alloy composition is changed, low phase stability can increase the formation of undesired precipitated phases.
Thermal Expansion
It is the phenomenon in which a material's length, volume, or lattice parameter changes when the temperature changes. It usually expands as temperature rises, but depending on composition or structure, very small or even negative values can also appear.
When designing low thermal expansion alloys, the linear thermal expansion coefficient is predicted according to temperature change.
Curie Temperature
It is the critical temperature at which spontaneous order such as ferromagnetism or ferroelectricity disappears due to thermal fluctuations. Above this temperature, the material's magnetic or polarization behavior changes significantly.
In Invar alloys, the Curie Temperature is an important property index when understanding the correlation between magnetism and thermal expansion.
Global Structure Search
A method that searches a broad space of possible structures under a given composition or condition to find the most stable structure or promising candidates. It uses multiple initial structures and search strategies so as not to be trapped in local minima.
Global Structure Search is carried out to find unknown compounds under high-pressure conditions.
Octahedral Crystal Field · Octahedral Field
The electronic level splitting and energy environment that arise when the ligand arrangement around a transition-metal ion has octahedral symmetry. It has a large influence on electron configuration, spin state, and magnetic properties.
When classifying 2D magnet candidates, Octahedral Crystal Field information can be used as a descriptor.
Order-Disorder Transition
A phase transition in which the arrangement of atoms or point defects changes between an ordered state and a disordered state. Depending on temperature, composition, and heat-treatment conditions, the microstructure and properties of a material can change significantly.
In alloy precipitation processes, the Order-Disorder Transition governs the formation of the initial phase.