Superconductivity typically emerges from strong interactions between electrons and vibrations in the crystal lattice (phonons). These interactions can lead to electron pairing, enabling resistance-free current flow. Our goal is to look for materials that show promising signs of these interactions at room temperature.
What: Calculate the most stable configuration of the material at 0K
Why: This gives us our starting point - like finding the "resting state" of the material
Details:
Use Quantum ESPRESSO to run DFT calculations
Need high accuracy because later steps build on this
Takes ~100-1000 CPU hours per material
Must ensure forces and energies are well converged
What: Carefully bring the material up to 300K
Why: Abruptly heating could shock the system and give unrealistic results
How:
Start from ground state
Gradually increase temperature over 5 picoseconds
Use velocity rescaling to control heating
Monitor system to ensure stable heating
What: Let the system stabilize at 300K
Why: Need to ensure the material is behaving normally at room temperature before measuring properties
Details:
Run for 45 picoseconds
Use Nosé-Hoover thermostat to maintain temperature
Check energy conservation
Watch for any structural instabilities
This is like letting a pot of water settle after bringing it to a boil
What: Collect data about how atoms move and electrons behave
Why: This is where we look for signatures of potential superconductivity
Technical Details:
Run for 30 picoseconds
Save data every 5 femtoseconds
Calculate Dynamic Structure Factor (DSF)
DSF tells us how atoms move collectively
Look for specific patterns in the DSF that suggest strong electron-phonon coupling
What: Analyze the DSF patterns
Why: Certain patterns suggest conditions favorable for superconductivity
Looking For:
Soft phonon modes (vibrations that become very easy to excite)
Strong peaks at specific wavelengths
Patterns similar to known superconductors
What: Rank materials based on how promising they look
Why: Need to prioritize which materials deserve deeper study
Method:
Compare DSF patterns to known superconductors
Look for strong electron-phonon coupling signatures
Consider chemical similarity to known superconductors
Assess practical feasibility of synthesis
Ground State: ~1000 CPU hours
AIMD Runs: ~10000 CPU hours
Analysis: ~50 CPU hours
Storage: ~10GB per material
2025-01-03