CP2K is a quantum chemistry and solid state physics software package that can perform atomistic simulations of solid state, liquid, molecular, periodic, material, crystal, and biological systems. CP2K provides a general framework for different modeling methods such as DFT using the mixed Gaussian and plane waves approaches GPW and GAPW. Supported theory levels include DFTB, LDA, GGA, MP2, RPA, semi-empirical methods (AM1, PM3, PM6, RM1, MNDO, …), and classical force fields (AMBER, CHARMM, …). CP2K can do simulations of molecular dynamics, metadynamics, Monte Carlo, Ehrenfest dynamics, vibrational analysis, core level spectroscopy, energy minimization, and transition state optimization using NEB or dimer method. (Detailed overview of features.)
CP2K is written in Fortran 2003 and can be run efficiently in parallel using a combination of multi-threading, MPI, and CUDA. It is freely available under the GPL license. It is therefore easy to give the code a try, and to make modifications as needed.
Please note that CP2K comes without any warranty or direct support.