dqmc-analyze

name	dqmc-analyze
description	Extract physical observables with error estimates from completed DQMC simulations. Use when computing density, double occupancy, spin correlations, structure factors, or any measured quantity from simulation data.

Analyze Results

Inputs

• Directory containing bin_*.h5 files (completed simulations)
• Observable names (see table below)

Outputs

• Dictionary with parameters and (mean, stderr) tuples for each observable

Procedure

Basic analysis:

from dqmc_util import analyze_hub

data = analyze_hub.get("data/run/", "sign", "den", "zzr")

print(f"sign = {data['sign'][0]:.4f} +/- {data['sign'][1]:.4f}")
print(f"density = {data['den'][0]:.4f} +/- {data['den'][1]:.4f}")

Available observables:

Name	Description	Requires
sign	Fermion sign	-
den	Density	-
docc	Double occupancy <n_up n_down>	-
gr, gk	Green's function (real/k-space)	-
nnr, nnq	Density correlator / structure factor	-
zzr, zzq	Spin-z correlator / structure factor	-
xxr	Spin-x correlator	-
swq0	S-wave pair structure factor	-
nnrw0, zzrw0	Zero-freq susceptibilities	period_uneqlt > 0
dwq0t	D-wave pair susceptibility	period_uneqlt > 0

Collect from multiple directories:

import os

def collect_results(base_dir, observables):
    results = []
    for subdir in sorted(os.listdir(base_dir)):
        path = os.path.join(base_dir, subdir)
        if os.path.isdir(path):
            try:
                results.append(analyze_hub.get(path + "/", *observables))
            except Exception as e:
                print(f"Skipping {path}: {e}")
    return results

Compute derived quantities:

# Magnetic moment squared from spin correlator
path = "data/run/"
data = analyze_hub.get(path, "zzr")
mz2 = 4 * data["zzr"][0][0, 0]       # [0] = mean, shape (Ny, Nx)
mz2_err = 4 * data["zzr"][1][0, 0]   # [1] = stderr

Validation

• Errorbar on sign is significantly less than mean. Otherwise, sign problem is too severe.
• Errorbars on observable are reasonable (not >> mean)

Failure Modes

Symptom	Cause	Recovery
KeyError for observable	Observable not computed	Check period_uneqlt setting
"No files found"	Wrong path or no bin_*.h5	Verify directory structure
Large error bars	Insufficient statistics	Run more sweeps or bins