凝態物理專題演講
Advanced Topics on Condensed Matter Physics
Department of Physics, NCU
Phonon Calculation Within Density Functional Perturbation Theory (DFPT)
Speaker
Icuk Setiyawati, PHD student
Department of Physics, National Central University
Date 2015.11.5 (Thur)
Time 14:00
Place S4-625
Abstract:
The lattice vibrations so called as the phonon commonly calculated within
Density Functional Theory via Interatomic Force Constants (IFC): Frozen-phonon technique (finite differentiation of forces), Density Functional Perturbation Theory (direct calculation of second order derivatives of the energy), and alternative methods non IFCs, the so called Molecular Dynamics where the phonon spectra can be extracted from MD runs via Fourier Transform of the velocity-velocity autocorrelation function. In this talk, I will focus on DFPT method. In the first part, I will explain the basic idea of the phonon calculation from diatomic linear chain
model, and in the second part I will explain how the perturbation theory take part in phonon calculation within DFPT methods. Lastly, I will explain the properties we can get from phonon calculation and how this phonon calculation is used in my current research.
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METADYNAMICS: FREE ENERGY RECONSTRUCTION & CONFORMATION SEARCH IN NANOMETALLIC GOLD CLUSTERS
Speaker
Lim Chong Chiat, M.Sc. Student
Department of Physics, National Central University
Date 2015.11.05 (Thur)
Time 15:00
Place S4-625
Abstract:
On the nanoscale, gold clusters possess different physical and chemical properties compared with their bulk counterparts, as a consequence of its electronic structure and the extremely small dimensions. Concerning the nano-sized gold particle has wide industrial applications, the description of its conformational space is a fundamental issue. Metadynamics, which is molecular-dynamics-based, is a powerful technique for enhancing specific configurational sampling as a function of collective variables. In this presentation, I give an introduction to nanoscale gold particles, and describe how the metadynamics is used to study this system, along with its related concepts.