in silico
Phase 1: In Silico Validation: Numerical verification of symmetry-enforced degeneracies and frequency predictions
- Objective
- To rapidly falsify the hypothesis by testing whether the predicted degeneracies (E-mode splitting < 10^{-3} c/a) and frequency predictions (A1 mode error < 1%) hold in high-resolution numerical simulations, before any experimental investment.
- Estimated cost
- €500-2000
- Estimated duration
- 4-6 weeks
- Success criteria
- E-mode splitting Δf_E at r=0.20a · Δf_E < 1×10^{-3} c/a for all n=10 runs · (Compute frequency difference between the two E-mode components from MPB output. Use two-tailed one-sample t-test against μ=0 (alpha=0.05).)
- Relative error of calibrated algebraic A1 frequency · |f_A1,algebraic - f_A1,PWE| / f_A1,PWE < 0.01 for all n=10 runs · (Compute relative error after applying calibration factor α. Use one-tailed one-sample t-test against μ=0.01 (alpha=0.05).)
- A1 frequency change with radius · Δf_A1 / f_A1,nominal < 0.05 for Δr/r = ±0.10 · (Compute f_A1 at r=0.18a and r=0.22a, compare to r=0.20a. Use two-tailed t-test (n=5 each, alpha=0.05).)
- E-mode splitting at r=0.18a and r=0.22a · Δf_E < 1×10^{-3} c/a for both radii · (Compute Δf_E at each radius. Use two-tailed t-test against threshold (n=5, alpha=0.05).)
- Go if
- All four success criteria are met (p-values > 0.05 for all tests, or thresholds satisfied for all runs).
- No-go if
- Any success criterion fails (e.g., Δf_E > 1×10^{-3} c/a in any run, or relative error > 1% in any run).
- Pivot if
- If only prediction 1 fails (E-mode splitting too large), investigate numerical convergence (increase basis to 512×512) and check for accidental degeneracies. If prediction 2 fails (A1 error > 1%), refine the algebraic projection method (use higher-order symmetry-adapted basis). If prediction 3 fails (radius sensitivity), consider that the calibration factor may be radius-dependent; test a radius-dependent calibration.
- Risks
- Numerical convergence not achieved at 256×256 basis (frequencies change > 1×10^{-4} c/a with larger basis)Probability: mediumMitigation: Increase basis to 512×512 (requires more RAM). Verify convergence by comparing 256×256 vs 512×512 results for a single run.
- Accidental degeneracy between A1 and E modes at Γ point (band crossing) confuses mode identificationProbability: lowMitigation: Use field pattern projection onto irrep basis functions to unambiguously assign symmetry. If crossing occurs, track bands across k-space.
- Random seed variability causes large variance in Δf_E (e.g., due to numerical noise)Probability: lowMitigation: Increase n to 20 runs. Use a more stable solver (MPB’s iterative eigensolver is deterministic; use different initial guesses instead of random seeds).
- Calibration factor α is not transferable to different radii (prediction 3 fails)Probability: mediumMitigation: If prediction 3 fails, compute α separately for each radius (defeats the purpose but still validates the algebraic method). Report as a limitation.