The latest version of MRCC is released on August 28, 2023.
The important new features and changes are as follows.

1. Reduced-cost explicitly correlated CCSD(T) approach. https://doi.org/10.1021/acs.jctc.2c01031

2. Analytic gradients for local density fitting Hartree-Fock and Kohn-Sham methods. https://doi.org/10.1063/5.0131683

3. Double-hybrid density functional theory for core excitations. https://doi.org/10.1021/acs.jctc.2c01222

4. Reduced-cost second-order ADC(2) method for core excitations. https://pubs.acs.org/doi/10.1021/acs.jctc.3c00101

5. Vertical ionization potentials and electron affinities at the double-hybrid density functional level. https://doi.org/10.1021/acs.jctc.3c00363

6. Implementation of the frozen natural orbital (FNO) approximation also for occupied orbitals and spatial symmetry adapted FNOs for reduced-cost general-order CC and CI methods.

7. Improved support of virtual subspace selection for projection-based and Huzinaga-equation-based DFT embedding.

8. Subsystem-localized projected atomic orbitals.

9. Unrestricted Hartree-Fock/Kohn-Sham formalism for projection-based and Huzinaga-equation-based DFT embedding.

10. Implementation of the density-based basis-set correction approach of Toulouse, Giner, and co-workers [J. Phys. Chem. Lett. 10, 2931 (2019)]

11. Implementation of the Davidson correction for MRCI.

12. Improved geometry optimizer.

13. Implementation of more efficient density fitting MP2 gradients.

14. Implementation of more efficient DFT integration grids.

15. A couple of bugs have been fixed, and the manual has been improved.

It is recommended for every user to upgrade to this version.