# Condensed Matter

> Properties of solid and liquid matter

- Skill: `ffsshhttiikk/condensed-matter` (Agent Skill)
- Install (CLI): `npx skillmds@latest add ffsshhttiikk/condensed-matter`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ffsshhttiikk/condensed-matter/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: MIT
- Author: ffsshhttiikk (https://skillmd.com/u/ffsshhttiikk)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/ffsshhttiikk/condensed-matter

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## What I do
- Analyze crystal structures and symmetry
- Model electronic band theory
- Study superconductivity and superfluidity
- Calculate phonon dispersion relations
- Analyze magnetic properties and phase transitions
- Apply density functional theory concepts

## When to use me
When studying solid-state physics, materials science, or semiconductor devices.

## Key Concepts
- **Crystal Lattices**: Bravais lattices, Miller indices for planes
- **Bloch's Theorem**: ψ_{k}(r) = e^{ik·r} u_k(r) for periodic potentials
- **Band Theory**: Energy bands arise from periodic potentials, band gaps
- **Fermi Surface**: Boundary between occupied and empty states at T=0
- **Phonons**: Quantized lattice vibrations, acoustic and optical modes
- ** BCS Theory**: Superconductivity from electron pairing below T_c