{"schema":"rtlab.benchmark.v1","id":"mgb2","generated":"2026-09-09","material":"hexagonal MgB2","name":"MgB\u2082","purpose":"Experiment 1 of the plan, computational half: reproduce a published reference (MgB2, the first literature anchor on the Tc landscape) with the same pipeline, and put the computed point next to the published one. LDA, norm-conserving, isotropic, tutorial-grade meshes: a reproduction attempt, not a converged calculation and not the anisotropic two-gap physics of MgB2.","material_prediction":false,"hypothesis_relevance":"reference reproduction only (experiment 1); MgB2 is not a hydride","executed":{"date":"2026-09-09","machine":"aarch64","host":"Raspberry Pi 5 at this site, 4 cores, 16 GB","hostname":null,"quantum_espresso":"7.4 (conda-forge, openmpi, openblas, fftw)","mpi_processes":4,"runtime_seconds":7624,"step_seconds":{"mgb2.scf.fit":41,"mgb2.scf":6,"mgb2.elph":7533,"mgb2.q2r":1,"mgb2.matdyn":43},"script":"scripts/rtlab/mgb2_benchmark.sh","analysis":"scripts/rtlab/qe_benchmark.py","raw_outputs":"public/rtlab/data/mgb2-benchmark/ (lambda, a2F.dos1..10, phonon.dos, inputs)"},"inputs":{"pseudopotentials":[{"file":"Mg.pz-n-vbc.UPF","sha256":"2e3c634dd5e71bde760e089882cfcf8d4ff1f166880d012dc3d6061d8f21816c","url":"https://pseudopotentials.quantum-espresso.org/upf_files/Mg.pz-n-vbc.UPF","type":"norm-conserving","functional":"LDA (Perdew-Zunger)"},{"file":"B.pz-vbc.UPF","sha256":"4011d1208df59cb001850b5f5ad45636059e3e6ae9d528d7dc78240b5218d833","url":"https://pseudopotentials.quantum-espresso.org/upf_files/B.pz-vbc.UPF","type":"norm-conserving","functional":"LDA (Perdew-Zunger)"}],"pseudopotential":{"file":"Mg.pz-n-vbc.UPF","sha256":"2e3c634dd5e71bde760e089882cfcf8d4ff1f166880d012dc3d6061d8f21816c","url":"https://pseudopotentials.quantum-espresso.org/upf_files/Mg.pz-n-vbc.UPF","type":"norm-conserving","functional":"LDA (Perdew-Zunger)"},"lattice":"hexagonal P6/mmm, a = 5.8260 bohr (3.083 \u00c5), c/a = 1.1420 (experimental cell, not relaxed); Mg at (0,0,0), B at (1/3,2/3,1/2) and (2/3,1/3,1/2)","ecutwfc_ry":40.0,"smearing":"Methfessel-Paxton 0.02 Ry","k_mesh_fit":[24,24,18],"k_mesh_scf":[12,12,9],"q_mesh":[6,6,3],"irreducible_q_points":14,"el_ph_sigma_ry":0.005,"el_ph_nsigma":10,"matdyn_k_mesh":[24,24,18],"matdyn_ndos":100,"fermi_energy_ev":7.437},"convergence_status":"NOT converged: these q meshes cannot resolve the E2g bond-stretching branch that carries most of the coupling in MgB2, lambda has no plateau against the double-delta smearing at these k meshes, and an isotropic alpha2F cannot reproduce the two-gap Tc. The other-mesh check shows how much lambda moves.","qe_lambda_table":[{"sigma_ry":0.005,"lambda_qe":0.9367,"dos_ef":4.4576,"omega_ln_k":634.1862,"omega_ln_mev":54.65},{"sigma_ry":0.01,"lambda_qe":0.8813,"dos_ef":4.7306,"omega_ln_k":641.8641,"omega_ln_mev":55.312},{"sigma_ry":0.015,"lambda_qe":0.8601,"dos_ef":4.7425,"omega_ln_k":642.0595,"omega_ln_mev":55.328},{"sigma_ry":0.02,"lambda_qe":0.8213,"dos_ef":4.707,"omega_ln_k":643.9478,"omega_ln_mev":55.491},{"sigma_ry":0.025,"lambda_qe":0.7832,"dos_ef":4.6601,"omega_ln_k":646.3361,"omega_ln_mev":55.697},{"sigma_ry":0.03,"lambda_qe":0.7492,"dos_ef":4.605,"omega_ln_k":648.9184,"omega_ln_mev":55.919},{"sigma_ry":0.035,"lambda_qe":0.7183,"dos_ef":4.5454,"omega_ln_k":651.5562,"omega_ln_mev":56.147},{"sigma_ry":0.04,"lambda_qe":0.6895,"dos_ef":4.4844,"omega_ln_k":654.1524,"omega_ln_mev":56.37},{"sigma_ry":0.045,"lambda_qe":0.6629,"dos_ef":4.4242,"omega_ln_k":656.6451,"omega_ln_mev":56.585},{"sigma_ry":0.05,"lambda_qe":0.6382,"dos_ef":4.3663,"omega_ln_k":659.0054,"omega_ln_mev":56.789}],"convergence_check":{"note":"The same recipe on the other mesh listed here (main record = the denser run); only the QE lambda table is recorded. Compare column by column with qe_lambda_table.","k_mesh_fit":[16,16,12],"k_mesh_scf":[8,8,6],"q_mesh":[4,4,3],"runtime_seconds":1473,"host":"this site's Raspberry Pi 5","qe_lambda_table":[{"sigma_ry":0.005,"lambda_qe":1.1978,"dos_ef":4.8597,"omega_ln_k":696.1642,"omega_ln_mev":59.991},{"sigma_ry":0.01,"lambda_qe":0.8488,"dos_ef":4.7928,"omega_ln_k":707.2731,"omega_ln_mev":60.948},{"sigma_ry":0.015,"lambda_qe":0.7623,"dos_ef":4.705,"omega_ln_k":707.9175,"omega_ln_mev":61.004},{"sigma_ry":0.02,"lambda_qe":0.7063,"dos_ef":4.6337,"omega_ln_k":708.161,"omega_ln_mev":61.025},{"sigma_ry":0.025,"lambda_qe":0.6698,"dos_ef":4.5994,"omega_ln_k":708.6033,"omega_ln_mev":61.063},{"sigma_ry":0.03,"lambda_qe":0.6425,"dos_ef":4.5686,"omega_ln_k":708.8714,"omega_ln_mev":61.086},{"sigma_ry":0.035,"lambda_qe":0.6187,"dos_ef":4.527,"omega_ln_k":708.7798,"omega_ln_mev":61.078},{"sigma_ry":0.04,"lambda_qe":0.5966,"dos_ef":4.4758,"omega_ln_k":708.3123,"omega_ln_mev":61.038},{"sigma_ry":0.045,"lambda_qe":0.576,"dos_ef":4.42,"omega_ln_k":707.5557,"omega_ln_mev":60.972},{"sigma_ry":0.05,"lambda_qe":0.5571,"dos_ef":4.3637,"omega_ln_k":706.6314,"omega_ln_mev":60.893}],"lambda_shift_at_chosen_sigma":0.0325,"lambda_shift_note":"main-record lambda minus other-mesh lambda at the chosen smearing"},"analysis_by_smearing":[{"sigma_ry":0.005,"lambda_integrated":0.9728,"omega_log_mev":55.355,"omega_2_mev":60.569,"allen_dynes_k":45.28,"eliashberg_k":49.891,"eliashberg_status":"model_solution"},{"sigma_ry":0.01,"lambda_integrated":0.899,"omega_log_mev":55.887,"omega_2_mev":60.517,"allen_dynes_k":39.795,"eliashberg_k":44.179,"eliashberg_status":"model_solution"},{"sigma_ry":0.015,"lambda_integrated":0.873,"omega_log_mev":55.878,"omega_2_mev":60.155,"allen_dynes_k":37.668,"eliashberg_k":41.988,"eliashberg_status":"model_solution"},{"sigma_ry":0.02,"lambda_integrated":0.8324,"omega_log_mev":56.031,"omega_2_mev":60.232,"allen_dynes_k":34.419,"eliashberg_k":38.604,"eliashberg_status":"model_solution"},{"sigma_ry":0.025,"lambda_integrated":0.7931,"omega_log_mev":56.228,"omega_2_mev":60.452,"allen_dynes_k":31.266,"eliashberg_k":35.313,"eliashberg_status":"model_solution"},{"sigma_ry":0.03,"lambda_integrated":0.7582,"omega_log_mev":56.441,"omega_2_mev":60.725,"allen_dynes_k":28.446,"eliashberg_k":32.332,"eliashberg_status":"model_solution"},{"sigma_ry":0.035,"lambda_integrated":0.7265,"omega_log_mev":56.656,"omega_2_mev":61.017,"allen_dynes_k":25.871,"eliashberg_k":29.634,"eliashberg_status":"model_solution"},{"sigma_ry":0.04,"lambda_integrated":0.6971,"omega_log_mev":56.865,"omega_2_mev":61.308,"allen_dynes_k":23.483,"eliashberg_k":27.11,"eliashberg_status":"model_solution"},{"sigma_ry":0.045,"lambda_integrated":0.6699,"omega_log_mev":57.067,"omega_2_mev":61.596,"allen_dynes_k":21.278,"eliashberg_k":24.757,"eliashberg_status":"model_solution"},{"sigma_ry":0.05,"lambda_integrated":0.6448,"omega_log_mev":57.259,"omega_2_mev":61.875,"allen_dynes_k":19.252,"eliashberg_k":22.613,"eliashberg_status":"model_solution"}],"chosen":{"sigma_ry":0.01,"why":"the smearing at which this mesh and the other mesh agree best on lambda (|delta| = 0.032 at sigma = 0.01 Ry; 0.005 Ry excluded as a known unconverged point). Across the whole smearing table lambda still runs from 0.64 to 0.94, so the criterion, not the table, is what pins the number; read both.","lambda_spread_three_smearings":0.0325,"criterion":"mesh agreement","spectrum_file":"data/mgb2-a2F.dat","spectrum_rows":100,"omega_max_mev":102.3,"lambda_integrated":0.899,"omega_log_mev":55.887,"omega_2_mev":60.517,"allen_dynes_k":39.795,"eliashberg_k":44.179,"eliashberg_status":"model_solution","solver":{"n_matsubara":512,"n_matsubara_why":"MgB2 solves near 30 to 40 K; 512 frequencies keep the resolved floor below 3 K at the 100 meV cutoff","cutoff_factor":10,"mu_star":0.1}},"reference":{"note":"Comparison values for MgB2, the first literature anchor on the Tc landscape.","measured_tc_k":39,"literature_lambda_isotropic":0.87,"literature_omega_log_mev":62.49,"literature_tc_k":40,"source":{"text":"Kong, Dolgov, Jepsen and Andersen, Phys. Rev. B 64, 020501(R) (2001): isotropic lambda 0.87, omega_ln 504 cm-1, Tc 40 K at mu* 0.10. Measured 39 K: Nagamatsu et al., Nature 410, 63 (2001).","doi":"10.1103/PhysRevB.64.020501","arxiv":"cond-mat/0102499","claims":["mgb2-lambda","mgb2-omegalog","mgb2-tc-calc","mgb2-tc-measured"]}},"toolkit":{"zip":"public/rtlab/downloads/rtlab-toolkit.zip","sha256":"e54e6e7f54e4ace4844e21a9767338bf97046c8222f4e6f316ef10dc339e4e68","command":"python -m rtlab analyze --spectrum mgb2-a2F.dat --frequency-unit meV --mu 0.10 --eliashberg --matsubara 512"},"python":"3.13.5"}