Author: reproduciblecrucible

How to Make a Supercell in VASP

I will explain how to make a supercell (that is, arbitrarily repeat a unit cell in space) for running simulations in VASP with a program called VESTA. VESTA can visualize the POSCAR and CONTCAR files that VASP uses to model atoms and molecules. Download VESTA: http://jp-minerals.org/vesta/en/ In my example, I will expand a graphene unit … Continue reading How to Make a Supercell in VASP →

Wavevectors, Dispersion Relations, and Clotheslines: Phonon Edition

In my experience taking solid state physics classes, esoteric concepts are constantly presented like they're completely self-evident. Of course, the dispersion relation of a material lays out valuable information that you understand immediately. Of course. Maybe you had a clearer professor than I did, but if you didn’t, I’ll cover my understanding of these concepts … Continue reading Wavevectors, Dispersion Relations, and Clotheslines: Phonon Edition →

Getting Started with VASP on XSEDE

VASP stands for Vienna ab initio Simulation Package. VASP is a popular implementation for DFT (density functional theory) modeling and can simulate atomic-scale behavior of materials. The gist of DFT is that it uses the Born-Oppenheimer approximation to separate the wavefunctions of the atomic nucleus and core electrons (ionic potentials) from the valence electrons (electronic … Continue reading Getting Started with VASP on XSEDE →

A Light-Hearted Introduction to Diffraction

Waves have amplitude and phase. Amplitude is the height of the wave and determines how much energy it carries. Depending on who you talk to, phase has different meanings. I would say that phase encompasses where a wave is in space and time. All waves—ocean waves, light, sound, electrons—diffract. Diffraction is when waves interact with … Continue reading A Light-Hearted Introduction to Diffraction →