Course Unit

Catalogue

Materials Science - classical particle approach

  • Unit Coordinator: Jacek Dziedzic
  • ECTS Credits: 6
  • Semester: 1
  • Year: 2
  • Campus: Gdansk University of Technology
  • Language: English
  • Aims:

    We introduce the basics of physics of materials, with particular attention to the relationships between atomic structure and macroscopic physical properties.

    Classical computational particle methods are covered, mainly the molecular dynamics (MD) approach -- its basic theory (integration of e.o.m.) and practicalities (potentials, boundary conditions, initialisation, neighbourhood, cut-off radius) followed by a brief tour of more advanced concepts of MD (rigid molecules, shell model, constrained dynamics, thermostats, barostats, Ewald method).

  • Content:

    Section devoted to physics of materials:

    Crystalline and glassy materials (short-range, medium-range and long-range order, radial and angular distribution functions); thermodynamics of phase transitions; glass transition; gels (classification and applications); quasicrystals; liquid crystals; auxetics.
    Basic concepts of crystallography (Bravais lattice, primitive and elementary cell, simple and complex lattice, Miller indices, etc.); symmetry operations; crystallographic point groups and space groups; models of amorphous systems (CRN, RCP, random-coil); reciprocal lattice and its properties; conditions for Bragg’s diffraction and Laue diffraction. Bonding in crystals (ionic, covalent, metallic, molecular and hydrogen); binding energies (lattice sums, Madelung energy, the Evjen method and Ewald method); luctuation-dissipation effects. Structural defects: point defects (Schottky, Frenkel, substitutions, vacancies, intercalations); line defects (screw and edge dislocations, Frank network, mechanisms of dislocation generation,  relationship with the strength of materials), planar defects (low-angle boundaries, stacking faults, twinning). Defects in the electronic structure (plasmons, excitons, polarons, magnons, F-centers). Lattice vibrations (mono- and diatomic chain, optical and acoustic branches, dispersion relations); normal vibrations; models of lattice heat capacity (classical, Einstein, Debye); the most significant anharmonic effects.
    Principles of the Drude model, electrical conductivity of metals, magnetoresistive effect and the Hall effect.
    The Fermi gas of free electrons, the Fermi-Dirac distribution, Fermi level and chemical potential, degenerate and non-degenerate gas, density of states, Wiedemann-Franz law.
    Thermoemission and cold emission from metal to vacuum; contact voltage.
    The model principles of the band theory; Bloch’s theorem; classification of solids on the basis of the band theory; effective mass and quasi-momentum.
    Dependence of electrical conductivity on temperature in semiconductors and metals (due to changes in the carrier densities and in the relaxation time). Deviations from Ohm’s law (collisional ionisation, Zener effect, Poole-Frenkel effect, Seld dependence of relaxation time).


    Section devoted to the molecular dynamics method:


    Motivation behind computational approaches to nanotechnology, continuum and particle methods, classical and quantum-based methods, scaling of computational effort.
    The molecular dynamics method, its advantages and limitations. Conservation of energy in Newtonian mechanics. Phase space and trajectories.
    Periodic, open and mixed boundary conditions, minimum image convention, quasiiniSnity, limitations of PBCs. Cut-off radius and its consequences. Hockney’s linked cells and Verlet neighbour list. Initializing an MD simulation (positions, velocities), skew start, equilibration.
    Integration of the equations of motion. Verlet, leapfrog and predictor-corrector methods. Sources of error in integrating the equations of motion.
    Visualization in MD, calculating macroscopic quantities (energy, temperature, virial, pressure, specific heat, RDF, ADF, S(k), MSD, D(T)).

    Potential and its relationship with force. General and particular forms of potentials. Selected potentials: LJ, Born-Mayer, harmonic, Morse, Stillinger-Weber, Sutton-Chen, GAFF, AMOEBA).

    Polarizability and shell models (Cochran, Fincham).
    Constrained dynamics, formal approach, SHAKE, RATTLE, QSHAKE.
    (Optionally): Rigid molecules in MD simulations, Euler angles, rotation matrix, vector transformations, quaternions.
    Coulombic interactions in MD, Ewald method.
    NVT and NpT ensembles, primitive thermostats, ESM and CSM thermo- and barostats: Andersen, Berendsen, Hoover-Evans, Nose-Hoover, Nose-Andersen, Parrinello-Rahman. (Optionally): Hybrid (QM/MM) methods.


  • Pre-requisites:

    Basic concepts of classical physics -- force, acceleration, potential. Basic knowledge of calculus (Riemann's integral, minimisation of a function, partial and total derivatives).

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