Molpro is a comprehensive system of ab initio programs for advanced molecular electronic structure calculations, designed and maintained by H.-J. Werner and P. J. Knowles, and containing contributions from many other authors.
The emphasis of MOLPRO is on highly accurate computations, with extensive treatment of the electron correlation problem through the CASPT2-F12, MRCI-F12, CCSD(T)-F12 and associated methods. These efficient explicitly correlated methods make it possible to obtain results with near complete basis set (CBS) limit accuracy using triple-zeta basis sets. Well parallelised and explicitly correlated local coupled-cluster methods [PNO-LCCSD(T)-F12] allow to easily compute highly accurate energies for molecules with 100-200 atoms.
Efficient DFT and TD-DFT methods with a very large number of density functionals are also available. Analytical gradient techniques and many molecular properties are implemented for a wide range of closed- and open-shell methods, both for ground and electronically excited states. Relativistic effects can be accounted for by using Douglas-Kroll-Hess and Breit-Pauli approaches or effective core potentials.
The reviews in doi:10.1002/wcms.82 and doi:10.1063/5.0005081 summarise with examples the capabilities of the package, and full details can be found in the users' manual.Molpro runs on all modern computing platforms, and is supported by graphical front-ends iMolpro and gmolpro. It is very easy to use for standard applications, but also includes many advanced options for expert applications. Molpro can also be used as a platform for development.
Molpro version 2025.1 has been released in February 2025. It contains new features and improvements, and the changes are summarised here. Any feedback regarding improvements of this version will be appreciated.
The graphical user input program, iMolpro, has now been ported to Windows, and provides a complete platform for using Molpro on Windows, MacOS and Linux, including the running of jobs both locally and on remote servers. iMolpro is open source and freely available, but requires Molpro to be installed locally. For further details, see here; Self-contained binaries for MacOS, Linux and Windows can be downloaded from here.
Version 2.7.0 of the graphical user interface gmolpro has been released in April 2025. Note that only the Mac version is bundled with Molpro. On Linux, you have to explicitly install Molpro. Preferably Molpro2025.1 should be used together with gmolpro 2.7.0.