Next-generation quantum chemistry software

VeloxChem [RLV+20] is a Python-based open source quantum chemistry software for contemporary and future hardware architectures. It features interactive program access through Jupyter notebooks as well as massively parallel calculations in high-performance computing (HPC) environments.

VeloxChem offers modeling of complex molecular systems by means of force-field molecular dynamics and polarizable embedding in combination with user-friendly support for automatized solvation and force-field derivations. It is an ideal platform for building simulation workflows and data-driven research [dGTBCB+25].

VeloxChem is education enabling, providing a means to explain and explore the theory underlying computational chemistry in a highly interactive manner [FDB+23]. It is science enabling, providing a means for accelerated method development in quantum chemistry [HNB25].

This manual gives a description of the installation process and basic usage of VeloxChem. A more comprehensive view of the ample opportunities for Python software interactions is provided in the eChem book [FDB+22].

Selected functionalities

• Kohn–Sham Density Functional Theory (DFT)

• Time-dependent DFT (TDDFT)

• Complex polarization propagator (CPP)

  • linear response functions

  • quadratic response functions

  • cubic response functions

• Potential energy surface (PES) exploration for ground and excited states

• Optical (UV/vis) and X-ray absorption (XAS, XPS)

• Two-photon absorption (TPA)

• Electronic circular dichroism (ECD)

• Polarizabilities and dispersion coefficients

• Vibrational spectroscopies

  • Infrared absorption (IR)

  • Raman spectroscopy

  • Resonance Raman spectroscopy (RRS)

• Classical methods

  • Molecular mechanics (MM)

  • Interpolation mechanics (IM)

  • Molecular dynamics (MD)

  • Conformational search

  • Polarizable embedding (PE)

  • Localized properties (LoProp, RESP)

  • Empirical valence bond (EVB)