from https://github.com/tencent-quantum-lab/TenCirChem

令人兴奋的功能

TenCirChem 的功能包括：

• 静态模块
  • 以极快的速度计算 UCCSD、kUpCCGSD、pUCCD
  • 通过 TensorCircuit 进行噪声电路模拟
  • 自定义积分、活性空间近似、RDM、GPU 支持等。
• 动态模块
  • 将 renormalizer 模型转换为量子位表示
  • 基于 JAX 的 VQA 算法
  • 内置模型：自旋玻色模型、吡嗪 S1/S2 内部转换动力学

TenCirChem is designed to be:

• Fast  
  • UCC speed is 10000x faster than other packages    
    • Example: H8 with 16 qubits in 2s (CPU). H10 with 20 qubits in 14s (GPU)
    • Achieved by analytical expansion of UCC factors and exploitation of symmetry
• Easy to hack
  • Avoid defining new classes and wrappers when possible
    • Example: Excitation operators are represented as tuple of int. An operator pool is simply a list of tuple
  • Minimal class inheritance hierarchy: at most two levels
  • Expose internal variables through class attributes

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from  http://qbics.info/home/qhome.html

Quantum Mechanics

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

  • Energy and gradient calculations.

  • LDA, GGA, meta GGA and hybrid functionals.

  • Flexible initial guess (fragment, symmetry broken) 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.

  • Accurate X-ray absorption spectroscopy.

• Energy decomposition analysis (EDA):

  • Ground and excited states.

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

• Wave functions are output in mwfn format.

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.

• Projected hybrid orbital (PHO):

  • 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.

Geometry Optimziation

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

• Frozen atoms are supported.

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:

  • Default (like bond length, coordination numbers) and self-defined collective variables (CV).

  • Metadynamics, adaptive biased force (ABF), and extended ABF.