Multiwfn is the most powerful wavefunction analysis program, supporting almost all of the most important wavefunction analysis methods. Multiwfn is free, open-source, high-efficient, very user-friendly and flexible. Windows (32/64bit XP/Vista/7/8), 64bit Linux and Mac OS X platforms are supported. All versions can be downloaded at Multiwfn website http://Multiwfn.codeplex.com. Multiwfn accepts several kinds of files for inputting wavefunction information: .wfn/.wfx (Conventional / Extended PROAIM wavefunction file), .molden (Molden input file), .31~.40 (NBO plot file), .fch (Gaussian formatted check file). Other file types such as Gaussian .cub file, DMol3 .grd file, .pdb, .xyz file and plain text file are acceptable for specific functions.