Material screening pipeline

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.

The Pipeline Steps

1. Ground State Calculation

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

2. Heating to Room Temperature

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

3. Equilibration Phase

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

4. Production Run & Analysis

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

5. Pattern Recognition

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

6. Screening Process

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

Resource Planning

Computing Needs:

• Ground State: ~1000 CPU hours

• AIMD Runs: ~10000 CPU hours

• Analysis: ~50 CPU hours

• Storage: ~10GB per material