Changes in default settings:
Single-node shared-memory parallelism becomes default and recommended for most jobs. New command line key -mpi is required to use distributed-memory MPI-parallel features (Section 2.8).
Pure basis functions are used by default with BASIS=GEN.
Default number of grid points in Lebedev grids in solvent models changed from 302 to 194 points (non-Hydrogen) and 110 points (Hydrogen) atoms.
Use of SWIG charges for SMx models.
Input format for XPol, SAPT and XSAPT, and MBE jobs has changed.
Use EDA2 as the default driver for ALMO-EDA.
Frozen core approximation no longer applied by default in RAS-CI calculations.
General improvements:
Increased availability of basis sets: High angular momentum basis functions (up to k-functions) supported for most SCF, RI-MP2, CC, EOM-CC, ADC calculations.
Streamlined input format for RI-SCF calculations.
Added the def2- family of density fitted (RI) basis sets for SCF and post-SCF calculations (Courtesy of Dr. Florian Weigend).
On-the-fly generation for the superposition of atomic densities guess for SCF (K. Fenk, J. Herbert).
Reintroduction of legacy ECPs without fitting.
Easy specification of basis sets on fragments, reading of basis sets from an external file (Z. Pei and Y. Shao).
Improvements to the DFT capabilities:
Support for analytic frequency calculations using meta-GGA density functinoals (available only with shared-memory parallelism).
Support for analytic frequency calculations using resolution-of-the-identity (density-fitted) Coulomb (available only with shared-memory parallelism).
Improved performance of analytic partial hessian calculations using DFT.
New density functionals: revM06, revM11 (P. Morgante and R. Peverati).
Improvements in implicit solvation models:
Revised PCM tessellation grids for improved performance (J. Herbert).
Improved performance of the general SCF program with SMx solvation models (Y. Mao).
New MP2 features:
Addition of regularized orbital-optimized second-order Møller-Plesset perturbation theory ($\kappa $-OOMP2) (J. Lee, M. Head-Gordon; Section 6.6.5).
Enhancements to the coupled-cluster package:
Damped response, dynamic polarizabilities for two-electron absorption using EOM-CC (K. Nanda and A.I. Krylov).
Improved evaluation of spin-orbit coupling constants across EOM-CC states (P. Pokhilko and A.I. Krylov).
Better handling of linear point groups in ADC and CC methods.
Improved performance of disk-based ADC/CC algorithms.
Projected and Voronoi CAP for CAP-EOM-CC/CC calculations (K. Bravaya, A. Kunitsa; Section 7.8.6).
Dynamic polarizabilities for CCSD and EOM-CCSD (K. Nanda, A.I. Krylov; Section 7.8.16.4).
New feaures for SOC calculation and analysis (P. Pokhilko, A.I. Krylov; Section 7.8.16.2).
Dyson orbitals for CVS-EOM-CCSD (M. Vidal, S. Coriani, A.I. Krylov; Section 7.8.5).
Improvements in energy decomposition analysis methods:
Added electron density difference (EDD) plots and the ETS-NOCV analysis (Y. Mao).
Added support for PCM and SMD solvation models in ALMO-EDA (Y. Mao).
Resolved several issues that caused instabilities in MP2-EDA calculations (Y. Mao).
New capabilities for explicit solvation modeling:
Polarizable Embedding (PE) Model for ground-state and ADC calculations (M. Scheurer; Section 12.8).
Other new methods and capabilities:
Incremental FCI method (P. Zimmerman).
Transition potential DFT for core-valence excitations.
Analytic evaluation of Raman intensities (Z. Pei and Y. Shao).