Qbics Features

Qbics is being actively developed. We are working hard to make this list of features longer everyday!

General

• Just a single precompiled executable, so can be used “out-of-box”.

• Parallelization: OpenMP, MPI, CUDA.

• Many exclusive methods are adding to Qbics.

Quantum Mechanics

• Hartree-Fock (HF) and density functional theory (DFT):

  • Energy and gradient calculations.

  • LDA, GGA, meta GGA and hybrid functionals.

  • Flexible initial guess for SCF.

  • More than 80 standard Gaussian basis sets and 3 pseudopotentials.

  • Self-defined basis sets and pseudopotentals.

• Target state optimization (TSO):

  • Arbitrary diabtic states.

  • Accurate valence, core, double, and long-range excited states.

• Energy decomposition analysis (EDA):

  • Ground and excited states.

  • Generalized Kohn-Sham (GKS) and TSO schemes.

  • Many-body EDA up to arbitrary order.

• Wave functions are output in mwfn format.

• Semiemprical methods:

  • NDDO: AM1, PM6, etc.

  • xTB: GFN1-xTB, GFN2-xTB.

Molecular Mechanics

• CHARMM force field:

  • Accept standard PDB, PSF and CHARMM force field formats.

  • Energy and gradient calculations.

  • Gas phase and periodic boundary condition (PBC).

  • Cutoff and partical mesh Ewald (PME) scheme for electrostatic interactions.

QM/MM

• Energy and gradient calculations.

• Arbitrary combinations of QM and MM methods.

• • Can tread arbitrary number of boundary covalent bonds in an elegant way: no manually adding or removing atoms are needed.

  • Reasonable electronic structures can be obtained.

  • In Qbics, PHO is implemented in a black-box way, meaning that it is highly easy to use.

Potential Energy Surface Exploration

• Geometry optimization with contraints.

• Transition state search: NEB, Dimer, QST2.

• Minimum energy crossing point (MECP) search.

• Path integral free energy perturbation (PI-FEP).

Molecular Dynamics

• All QM, MM, and QM/MM methods can be used.

• NVE, NVT, and NPT ensembles.

• Enthalpy and entropy separation.

• Several restraint potentials.

• Free energy perturbation (FEP):

  • Single- and double-topology.

  • Reaction coordinates.

  • Charge transfer reactions.

• Enhanced sampling methods: metadynamic, umbrella sampling.