BALLView

BALLView is a standalone molecular modeling and visualization application. Furthermore it is also a framework for developing molecular visualization functionality.

It is available free of charge under the GPL for Linux, Windows and MacOS.
BALLView is a free molecular modeling and molecular graphics tool. It provides fast OpenGL-based visualization of molecular structures, molecular mechanics methods (minimization, MD simulation using the AMBER, CHARMM, and MMFF94 force fields), molecular editing, as well as calculation and visualization of electrostatic properties (FDPB).