• molecular cluster generation;
  • quantum mechanics/molecular mechanics;
  • nucleus-independent chemical shift;
  • computer programs

A new program, CLUSTERGEN, for molecular cluster generation is introduced. CLUSTERGEN provides the quantum mechanics/molecular mechanics (QM/MM) input files for program packages such as ADF [Baerends et al. (2012). Vrije Universiteit, Amsterdam, The Netherlands] and GAUSSIAN [Frisch et al. (2009). Gaussian Inc., Pittsburgh, Pennsylvania, USA]. Additionally, it prints out a standard CRYSTAL [Dovesi et al. (2009). University of Turin, Italy] input and, in general, facilitates file-format manipulation. The CLUSTERGEN program is supported by an extensive manual and a user-friendly graphical interface. The code is freely available and carefully commented, which makes it easily modifiable. Exemplary applications of CLUSTERGEN concerning QM/MM calculations and derivation of nucleus-independent chemical shift indices are demonstrated.