Welcome to ChemShell

ChemShell is a scriptable computational chemistry environment for multiscale modelling. While it supports standard quantum chemical or force field calculations, its main strength lies in hybrid QM/MM calculations. The concept is to leave the time-consuming energy evaluation to external specialised codes, while ChemShell takes over the communication and data handling.

Summary of Capabilities

• Interfaces to a variety of QM and MM codes, including
  
  • GAMESS-UK
  • NWChem
  • FHI-aims
  • DALTON
  • MNDO
  • TURBOMOLE
  • Orca
  • Molpro
  • Gaussian
  • DMol3
  • Q-Chem
  • DL_POLY
  • GULP
  • CHARMM
  • GROMOS
• The above codes can be used in hybrid QM/MM coupling using an additive scheme. The coupling models implemented in ChemShell include:
  • Mechanical Embedding
  • Electrostatic Embedding
  • Solid-state embedding scheme using shell model potentials (GAMESS-UK/NWChem + GULP)
• A range of geometry optimisers for finding minima and transition states, including a linear-scaling delocalised coordinate algorithm
• MD driver, incorporating NVE, NVT, NPT, and MC integration, rigid body motion (quaternions), distance and other constraints (SHAKE)
• Utilities:
  
  • Internal coordinate definition and manipulation
  • Mapping of potential energy surfaces
  • Finite difference vibrational frequencies
  • Restraints for umbrella sampling and complex potential energy surface scans
  • Evaluation of ESP and RESP charges from some QM codes that do not support this