Psi4 1.1: An Open-Source Electronic Structure Program
A recent paper describes Psi4 1.1: An Open-Source Electronic Structure Program Emphasizing Automation, Advanced Libraries, and Interoperability DOI
Psi4 is an ab initio electronic structure program providing methods such as Hartree–Fock, density functional theory, configuration interaction, and coupled-cluster theory. The 1.1 release represents a major update meant to automate complex tasks, such as geometry optimization using complete-basis-set extrapolation or focal-point methods. Conversion of the top-level code to a Python module means that Psi4 can now be used in complex workflows alongside other Python tools.
Psi4 1.1 can be downloaded from here with versions supporting Python 2.7, 3.5 and 3.6.
Note the installation instructions for Mac: Install XCode via the App Store, Make sure you open XCode and accept the license agreement after you install.