Tutorials

This section contains in-depth tutorials for using QuasiX.

Note

Tutorials are organized by complexity, from basic to advanced.

Getting Started

Start with these tutorials if you are new to QuasiX:

Basic G0W0 Calculation - Your first quasiparticle calculation
Comparing Starting Points - Understanding HF, PBE, PBE0 starting points
evGW for Better Accuracy - When and how to use self-consistent GW

Available Tutorials

Basic Tutorials

Advanced Topics

Benchmark Reproduction

GW100 Benchmark Guide

Planned Tutorials

The following tutorials are under development:

GW100 Benchmark Reproduction - Step-by-step guide to reproducing published results
Basis Set Convergence Studies - How to assess basis set completeness
Frequency Integration Parameters - Optimizing frequency grids
Performance Optimization Tips - Getting the best performance from QuasiX
Large System Calculations - Strategies for molecules with 100+ atoms
Periodic Systems - GW/BSE for crystals (coming in v1.0)

Example Gallery

Quick examples demonstrating specific features:

G0W0 Ionization Potential

from quasix import G0W0Driver
from pyscf import gto, scf

mol = gto.M(atom='H 0 0 0; H 0 0 0.74', basis='def2-tzvp')
mf = scf.RHF(mol).run()

gw = G0W0Driver(mf)
result = gw.kernel()

# Ionization potential (negative of HOMO)
IP = -result.homo_qp
print(f"Ionization Potential: {IP:.3f} eV")

Optical Gap from BSE

from quasix import G0W0Driver, BSEDriver
from pyscf import gto, dft

mol = gto.M(atom='...', basis='def2-svp')
mf = dft.RKS(mol)
mf.xc = 'pbe0'
mf.run()

gw = G0W0Driver(mf).kernel()
bse = BSEDriver(mf, gw_result=gw, n_states=5)
result = bse.kernel()

print(f"Optical gap: {result.excitation_energies[0]:.3f} eV")

Exciton Binding Energy

# After GW and BSE calculations
qp_gap = gw_result.gap_qp
optical_gap = bse_result.excitation_energies[0]
binding = qp_gap - optical_gap

print(f"QP gap: {qp_gap:.3f} eV")
print(f"Optical gap: {optical_gap:.3f} eV")
print(f"Exciton binding: {binding:.3f} eV")