Capabilities

This page summarizes what Quantas can currently do, which approximations are implemented, and which outputs are produced.

Scientific modules

HA

The harmonic workflow computes vibrational thermodynamic properties from phonon frequencies and q-point weights. Quantas reports quantities such as Helmholtz free energy, internal energy, entropy, zero-point energy, and isochoric heat capacity.

QHA

The quasi-harmonic workflow extends the harmonic approximation by considering how phonon frequencies or thermodynamic quantities evolve with volume. Quantas supports frequency-based and thermodynamic interpolation schemes, free-energy minimization, and derived properties such as \(\alpha_V\), \(C_P\), \(K_T\), and \(K_S\).

Elasticity

The elasticity workflow analyzes second-order elastic tensors. It covers stability, Voigt–Reuss–Hill averages, bulk and shear moduli, compliance, directional mechanical properties, exact directional extrema, tensor rotation, and 2D/3D visualizations.

SEISMIC

The seismic workflow uses the elastic tensor and density to solve the Christoffel equation and derive phase velocity, group velocity, polarization, enhancement, and other directional observables relevant to acoustic and geophysical analysis.

EOS

The equation-of-state workflow fits and evaluates models in the P–V, V–T, and P–V–T domains. Quantas supports OLS, WLS, effective variance, and ODR, with native HDF5 archives, diagnostics, and plotting.

Thermoelasticity

The thermoelastic workflow couples quasi-harmonic and elastic information to construct \(C_{ijkl}(P,T)\) in the quasi-static approximation. Point, Grid, and Profile analyses are supported, together with isothermal-to- adiabatic conversion and export to SEISMIC.

Shared outputs

Across workflows, Quantas can provide:

  • frontend-neutral report tables;

  • frontend-neutral plot specifications;

  • native HDF5 result archives with normalized inputs and provenance;

  • deterministic plain-text logs;

  • workflow-specific export files such as CSV tables or SEISMIC-ready inputs.

What is new in Quantas 2.0

Compared with the historical Quantas 0.9 series, Quantas 2.0 introduces:

  • a stable public Python API under quantas.api;

  • complete separation between numerical core and frontend adapters;

  • Click/Rich CLI with grouped options and neutral reporting contracts;

  • native HDF5 persistence across workflows;

  • explicit interoperability between modules;

  • a stronger documentation architecture oriented around theory, workflows, tutorials, and reference sections;

  • a codebase prepared for a future GUI without changing the scientific core.

For a concise historical comparison, see Changes from Quantas 0.9.