• New functionality with ExaCorr:
  • Calculation of linear response properties with CCSD wavefunctions.
    • Contributors: Xiang Yuan, Loic Halbert, Johann Pototschnig, Anastasios Papadopoulos, Lucas Visscher and Andre Gomes.
    • Reference: Xiang Yuan, Loic Halbert, Johann Valentin Pototschnig, Anastasios Papadopoulos, Sonia Coriani, Lucas Visscher, and Andre Severo Pereira Gomes, Formulation and Implementation of Frequency-Dependent Linear Response Properties with Relativistic Coupled Cluster Theory for GPU-Accelerated Computer Architectures, J. Chem. Theory Comput. 20, 677 (2024) https://doi.org/10.1021/acs.jctc.3c00812
    • Manual: CCCILR https://diracprogram.org/doc/release-24/manual/wave_function/exacorr.html#cccilr
    • Tutorial: not yet available; please have a look at examples in the testset.
  • Calculation of quadratic response properties CCSD wavefunctions.
    • Contributors: Xiang Yuan, Loic Halbert, Lucas Visscher and Andre Gomes.
    • Reference: Xiang Yuan, Loic Halbert, Lucas Visscher, and Andre Severo Pereira Gomes, Frequency-Dependent Quadratic Response Properties and Two-Photon Absorption from Relativistic Equation-of-Motion Coupled Cluster Theory, J. Chem. Theory Comput. 19, 9248 (2023) https://doi.org/10.1021/acs.jctc.3c01011
    • Manual: CCCIQR https://diracprogram.org/doc/release-24/manual/wave_function/exacorr.html#ccciqr
    • Tutorial: not yet available; please have a look at examples in the testset.
  • Calculation of energies with equation of motion coupled cluster for excitation (EOM-EE-CCSD), ionization (EOM-IP-CCSD), and electron affinity (EOM-EA-CCSD) models.
    • Contributors: Xiang Yuan, Loic Halbert, Lucas Visscher and Andre Gomes.
    • Reference: Xiang Yuan, PhD thesis (2024), https://doi.org/10.5463/thesis.505
    • Manual: EXEOM https://diracprogram.org/doc/release-24/manual/wave_function/exacorr.html#exeom see also https://www.diracprogram.org/doc/release-24/manual/wave_function/exacorr.html#id10
    • Tutorial: not yet available; please have a look at examples in the testset.
  • Two-body reduced density matrix for CCSD ground-state wavefunctions.
    • Contributors: Loic Halbert, Andre Gomes
    • Manual: GS2RDM https://diracprogram.org/doc/release-24/manual/wave_function/exacorr.html#gs2rdm
    • Tutorial: not yet available; please have a look at examples in the testset.

• Restart from density matrices of CC for first-order properties.
  • Contributors: Trond Saue, Andre Gomes
    • Manual: RDCCDM https://diracprogram.org/doc/release-24/manual/properties.html#rdccdm
• Update of DIRAC schema which defines the information stored on CHECKPOINT.h5.
  • Essential symmetry information added.
  • MO coefficients for C₁ symmetry optionally stored for restarts without use of symmetry.
  • Occupation of spinors in SCF added.
  • Non-default property integrals stored on separate file to reduce the size of the checkpoint file.
  • Copy of input files stored.
  • Contributors: Lucas Visscher, Trond Saue

• Support for AMD GPUs with ExaCorr (TAL-SH, work in progress to enable distributed calculations with ExaTensor), in addition to the NVIDIA GPU support (TAL-SH and ExaTensor).
  • Contributors: Johann Pototschnig, Jan Brandejs and Andre Gomes.
  • For further information on ExaTensor and TAL-SH as used in DIRAC, see https://github.com/RelMBdev/ExaTENSOR/tree/dirac
    • Note : ROCM versions 5.7+ should be used. Earlier ROCM versions may result in code that compiles but may show runtime errors (e.g. HSA_STATUS_ERROR_MEMORY_APERTURE_VIOLATION, or values different than reference ones in the tests). A potential workaround for earlier versions is to reduce hipcc optimization level to -O1.

• Calculation of Parity-Violating Nuclear Spin-Rotation Tensors. Activated with “.PVCSR”
  • Contributor: I. Agustín Aucar.
  • Reference: Ignacio Agustín Aucar and Anastasia Borschevsky, Relativistic study of parity-violating nuclear spin-rotation tensors. J. Chem. Phys. 155, 134307 (2021) https://doi.org/10.1063/5.0065487
  • Manual: PVCSR http://www.diracprogram.org/doc/release-23/manual/properties.html#pvcsr
  • Tutorial: http://www.diracprogram.org/doc/release-23/tutorials/pvcsr/tutorial.html

• Calculation of oscillator strengths beyond the electric dipole approximation in the generalized velocity representation
  • Contributors: Martin van Horn, Trond Saue, and Nanna Holmgaard List.
  • Reference: M. van Horn, T. Saue, N. H. List. Probing Chirality across the Electromagnetic Spectrum with the Full Semi-Classical Light-Matter Interaction. J. Chem. Phys. 156, 054113 (2022) https://doi.org/10.1063/5.0077502
  • Manual: VPOL http://www.diracprogram.org/doc/release-23/manual/properties/excitation.html#vpole
  • Tutorial: http://www.diracprogram.org/doc/release-23/tutorials/x_ray/BED_Ba/tutorial.html

• (e)amfX2C (improvement of AMFI): (extended) atomic-mean-field two-electron scalar and spin-orbit picture-change corrections for two-component Hamiltonian calculations
  • Contributors: Stefan Knecht, Michal Repsiky, Hans Joergen Aa. Jensen and Trond Saue.
  • Reference: Stefan Knecht, Michal Repisky, Hans Jørgen Aagaard Jensen, and Trond Saue, Exact two-component Hamiltonians for relativistic quantum chemistry: Two-electron picture-change corrections made simple, J. Chem. Phys. 157, 114106 (2022) https://doi.org/10.1063/5.0095112
  • Manual: XAMFI http://www.diracprogram.org/doc/release-23/manual/xamfi.html
  • Tutorial: http://www.diracprogram.org/doc/release-23/tutorials/two_component_hamiltonians/xamfX2C.html

• ExaCorr module works now also with contracted basis functions.
  • Contributor: Lucas Visscher.

• Basis set library has been extended with basis sets with diffuse functions for s and d blocks, dyall.aXNz basis sets. The Dyall basis sets can now be downloaded from the zenodo repository.
  • Contributor: Ken Dyall.

• HDF5 checkpoint file is now default for data handling
  • Contributor: Lucas Visscher
  • User manual: Data storage in DIRAC http://www.diracprogram.org/doc/release-23/manual/data.html
  • Developer manual: The CHECKPOINT.h5 file http://www.diracprogram.org/doc/release-23/development/checkpoint.html

• Added a CI gradient convergence threshold option '.THRGCI' to '\*KRCICALC' (could not be changed by user previously).
  • Contributor: H. J. Aa. Jensen.

• Improved code in luciarel CI program. Note that KRMC and KRCI by default uses luciarel.
  • Contributor: Andreas Nyvang.
  • numerical stability has been improved in the complex parallel diagonalization routine
  • convergence algorithm has also been changed, with considerable improvement in convergence rate. In particular, the truncation of the reduced space in the Davidson iterations is now done in a much better way, leading to the improvement in convergence rate. Both for real and complex parallel cases.

• Default for .MVO has been corrected, so it now behaves as expected: modified virtual orbitals based on the Fock potential from the doubly-occupied molecular orbitals after an open-shell SCF calculation (H. J. Aa. Jensen).

• New licence : GNU Lesser General Public License v2.1only
• Electronic circular dichroism (ECD) beyond lowest-order – full light-matter interaction. Contributors: Martin van Horn, Trond Saue and Nanna Holmgaard List
  • Reference : M. van Horn, T. Saue, N. H. List. Probing Chirality across the Electromagnetic Spectrum with the Full Semiclassical Light-Matter Interaction. J. Chem. Phys. (in press) (2022) ChemRxiv
  • Manual:
• MP2 frozen virtual natural orbitals via the ExaCorr module.
• Contributors: Xiang Yuan, Lucas Visscher, André Severo Pereira Gomes.
  • Reference: X. Yuan, L. Visscher, A. S. P. Gomes. Assessing MP2 frozen natural orbitals in relativistic correlated electronic structure calculations. arxiv.org/abs/2202.01146
  • Manual: .MP2NO and .DONATORB
• Polarizable Embedding with Complex Polarization Propagator.
• Contributors: Joel Creutzberg, Erik D. Hedegård
  • Reference: Polarizable embedding complex polarization propagator in four- and two-component frameworks. arXiv:2112.07721
  • Manual: *PEQM and tutorial PE-TDDFT calculations of excitation energies and solvent shifts¶

• HDF5 checkpoint file and DIRAC data scheme, python utilities to extract data.
• Contributor: Lucas Visscher
• Manual: The CHECKPOINT.h5 file

• DIIS replaced by CROP algorithm in ExaCorr module. Contributors: Chima Chibueze and Lucas Visscher.
  • Reference ExaCorr: J.V. Pototschnig et al., J. Chem. Theory Comput. 17 (2021) 5509−5529.
  • Manual: EXACC

• Molecular rotational g-tensors. Contributor: I. Agustín Aucar.
  • Reference: I. A. Aucar, S. S. Gómez, C. G. Giribet and M. C. Ruiz de Azúa. Theoretical study of the relativistic molecular rotational g-tensor.J. Chem. Phys. 141 (2014) 194103
  • Manual: ".ROTG"
  • Tutorial: Molecular rotational g-tensors
• ExaCorr GPU-aware parallel coupled cluster module. Contributors: Johann V. Pototschnig, Anastasios Papadopoulos, Dmitry I. Lyakh, Michal Repisky, Loïc Halbert, André Severo Pereira Gomes, Hans Jørgen Aa. Jensen, Lucas Visscher.
  • Reference: J. V. Pototschnig, A. Papadopoulos, D. I. Lyakh, M. Repisky, L. Halbert, A. S. P. Gomes, H. J. Aa. Jensen, L. Visscher. Implementation of relativistic coupled cluster theory for massively parallel GPU-accelerated computing architectures. arXiv:2103.08473 [physics.chem-ph]
  • Manual: "**EXACC"
• Atomic supersymmetry. Contributors: A. Sunaga and T. Saue
  • Manual: ".KPSELE"
  • Tutorial: Converging atoms
• Beyond the electric-dipole approximation When calculating excitation energies at the Hartree-Fock or Kohn-Sham levels, intensities can be calculated using the full semi-classical light-matter interaction as well as truncated interaction to arbitrary order in the wave vector in both the length and velocity representation. Rotational average is provided by default, but specific orientations can also be chosen. Contributors: Nanna H. List and Trond Saue
  • Reference: Nanna Holmgaard List, Timothé Romain Léo Melin, Martin van Horn and Trond Saue: Beyond the electric-dipole approximation in simulations of X-ray absorption spectroscopy: Lessons from relativistic theory, J. Chem. Phys. 152 (2020) 184110
  • Manual: ".BED"
  • Tutorial: coming soon

• Gauge origin, dipole origin, and phase origin (.GAUGEO alias .GO ANG, .DIPORG, and .PHASEO, respectively) can now ONLY be set under **HAMILTONIAN.

• Interface to ROSE (Localized Orbitals). Main contributor: Bruno Senjean.
  • Reference: B. Senjean, S. Sen, M. Repisky, G. Knizia, L. Visscher. Generalization of Intrinsic Orbitals to Kramers-Paired Quaternion Spinors, Molecular Fragments, and Valence Virtual Spinors. J. Chem. Theory Comput. 17 (2021) 1337–1354
  • ROSE repository (including documentation): gitlab.com/quantum_rose
• Extract DIRAC data to Python (see utils/dirac_data.py). Contributor: L. Visscher.

• Significantly improved performance of GASCIP configuration interaction module. Contributor: Hans Jørgen Aa. Jensen

• The format of the DFCOEF coefficient file has changed. You can convert old-style files to the new format using the utility routine cf_addlabels.x found in the the build directory after make.
• The CODATA2018 set of physical constants is now used as default. Values are taken from NIST web page (http://physics.nist.gov/constants). Before DIRAC21, values from CODATA1998 were default. New keyword was implemented to select the desired set of data. Contributor: Agustín Aucar
  • Manual: ".CODATA"
• In the compilation step OpenMP is now enabled by default.
• One-electron operator ANGMOM's origin was moved from gauge-origin to the molecular center of mass.

• Atomic supersymmetry does not work in combination with the molecular-mean-field X2C approach.
• ExaTensor (ExaCorr module) doesn't raise an error if it runs out of memory, but hangs

• EOMCC - core excitation and ionization energies via core-valence separation using projectors in RELCC (Avijit Shee, Andre Gomes, Marta Lopez Vidal)
  • Reference: L. Halbert, M. L. Vidal, A. Shee, S. Coriani, A. S. P. Gomes Relativistic EOM-CCSD for Core-Excited and Core-Ionized State Energies Based on the Four-Component Dirac–Coulomb(−Gaunt) HamiltonianJ. Chem. Theory Comput. 17 (2021), 3583
  • Manual: see keywords under "*CCPROJ"
• Python interface of DIRAC with Openfermion (Bruno Senjean) to perform relativistic quantum chemistry calculations simulated on a quantum computer .
• Nuclear Spin-Rotation tensors. Contributors: I. Agustin Aucar and Trond Saue.
  • Reference: I. A. Aucar, S. S. Gómez, M. C. Ruiz de Azúa, and C. G. Giribet. Theoretical study of the nuclear spin-molecular rotation coupling for relativistic electrons and non-relativistic nuclei.J. Chem. Phys. 136 (2012) 204119
  • Manual: ".SPIN-R"
  • Tutorial: Nuclear spin-rotation constants
• Nuclear Magnetic-Quadrupole-Moment interaction constant in KRCI (Malaya K. Nayak)
  • Reference: T. Fleig, M. K. Nayak and M. G. Kozlov TaN, a molecular system for probing P,T-violating hadron physics.Phys. Rev. A 93 (2016) 012505

• Improved root tracking for EOM-CC (Luuk)
• Use Kramers conjugation on doubly degenerate CI vectors in GASCIP code (cuts time for CI in half for ESR doublets) (Hans Jørgen)

• DFT magnetizatibilities with LAOS and symmetry (Gosia Oejniczak and Trond Saue)
• Resolved runtime issues in KRCI property modules (Malaya K. Nayak)

• Upgrade to python3

• DFT magnetizabilities. Contributors: M. Olejniczak and Trond Saue.
  • Limitations: Magnetizabilities and NMR shieldings calculated at the DFT level are so far restricted to C1 symmetry, but we expect to fix this soon.

• Enhancements to the frozen density embedding (FDE) functionality
  • FDE contributions to magnetic properties (NMR shieldings, indirect spin-spin coupling constants, magnetizabilities), see ".FDE" and "*FDE" entries of the manual for details. Contributors: M. Olejniczak, R. Bast, A. S. P. Gomes
    • References:
      • M. Olejniczak, R. Bast, A. S. P. Gomes On the calculation of second-order magnetic properties using subsystem approaches in a relativistic framework. Phys. Chem. Chem. Phys. 19 (2017) 8400
    • Tutorials:
      • NMR shieldings in Frozen Density Embedding (FDE) scheme with London atomic orbitals (LAOs)
  • FDE interaction energies with CCSD, MP2 and mean-field densities. Contributors: M. Olejniczak, A. Shee, R. Bast, A. S. P. Gomes
• Equation of motion coupled cluster
  • Energies for electronic excitations (EE), electron attachment (EA) and electron detachment (IP), see ".EOMCC", "*EOMCC" and "*CCDIAG" entries of the manual for details. Contributiors: A. Shee, T. Saue, L. Visscher, A. S. P. Gomes
    • References:
      • A. Shee, T. Saue, L. Visscher, A. S. P. Gomes Equation-of-motion coupled-cluster theory based on the 4-component Dirac-Coulomb(-Gaunt) Hamiltonian. Energies for single electron detachment, attachment, and electronically excited states. J. Chem. Phys. 149 (2018) 174113

• Polarized embedding can be done with xyz-files. Contributor: Trond Saue
• Improved quaternion diagonalization Contributor: H. J. Aa. Jensen
• Improvements in the visualization module (**VISUAL) Contributors: M. Olejniczak and T. Saue.
  • the possibility to calculate the NMR shielding tensor in a selected point in space, see ".NICS"
  • the possibility to visualize various densities on an imported 3D grid, see ".3D_IMP"
  • the possibility to calculate magnetic properties densities using the imported magnetically-induced current density, see ".READJB"
  • the possibility to scale densities by Cartesian products xⁱy^jz^k, see ".CARPOW"
  • the possibility to generate and visualize radial distributions, see ".RADIAL"

• New convergence criterium for CC amplitude equation: The convergence criterium for the amplitude equations that determine the CC energy has been revised and made consistent with the criterium used in the lambda equations used for molecular properties. In both cases we now take the norm of the differences between amplitudes of subsequent iterations. In practice this typically means the program will use a few iterations less. For normal calculations this is of no consequence as the default is still to converge very tightly, but if extremely high precision is required one may need to check the achieved convergence.
• Change in the reorthonormalization terms in the calculation of magnetic properties with London atomic orbitals: the reorthonormalization and response contributions involve the same orbital pairs, for instance if all rotations between occupied and virtual orbitals are present in response equations, the reorthonormalization terms are also constructed from all orbital blocks; the keywords .DOEPRN and .NOEPRN under *NMR are depreciated;

• Kramers-restricted Polarization Propagator in the ADC framework for electronic excitations, activated with ”.POLPRP”.
  • References:
    • M. Pernpointner. The relativistic polarization propagator for the calculation of electronic excitations in heavy systems. J. Chem. Phys. 140, 084108 (2014)
    • M. Pernpointner, L. Visscher and A. B. Trofimov. Four-component Polarization Propagator Calculations of Electron Excitations: Spectroscopic Implications of Spin-Orbit Coupling Effects. J. Chem. Theory Comput. 14, 1510 (2017).
  • Tutorials:
    • Computing Electronic Excitations using the Propagator Module POLPRP
    • Full scope application of POLPRP to an osmium carbonyl complex

• New expectation values in the KRCI module:
  • Magnetic hyperfine interaction.
    • Reference: T. Fleig and M. K. Nayak. Electron electric dipole moment and hyperfine interaction constants for ThO. J. Mol. Spectrosc., 300:16, 2014
  • Electron electric dipole moment interaction.
    • Reference: see T. Fleig and M. K. Nayak. Electron electric-dipole-moment interaction constant for HfF⁺ from relativistic correlated all-electron theory. Phys. Rev. A, 88:032514, 2013
  • Nucleon-electron scalar-pseudoscalar interaction.
    • Reference: M. Denis, M. Nørby, H. J. Aa . Jensen, A. S. P. Gomes, M. K. Nayak, S. Knecht, and T. Fleig. Theoretical study on ThF⁺, a prospective system in search of time-reversal violation. New J. Phys., 17:043005, 2015

• Polarizable embedding using pelib.
  • Reference: E. D. Hedegård, R. Bast, J. Kongsted, J. M. H. Olsen, and H. J. Aa. Jensen. Relativistic Polarizable Embedding. J. Chem. Theory Comput. 13, 2870-2880 (2017)
  • Tutorials:
    • A Hartree-Fock calculation with the polarizable embedding (PE) model
    • Properties in solution: PE-TDDFT calculations of excitation energies and solvent shifts

• New ”.MVOFAC” option in *KRMC input section for Modified Virtual Orbitals in MCSCF. Contributor: H. J. Aa. Jensen.

• New and numerically stable procedure for elimination/freezing of orbitals at SCF level. Contributor: T. Saue.

• Support for use of DIRAC in PyADF and QMFlows workflow engines. Contributors: Lucas Visscher, Andre Gomes and Christoph Jacob

• New easier options for point charges in the .mol file: “LARGE POINTCHARGE” or “LARGE NOBASIS” (the two choices are equivalent), see here

• Provided memory counter for RelCC calculations, suitable for memory consuming large scale Coupled Cluster calculations, see here for details. Contributor: Miroslav Iliaš

• Write out effective Hamiltonian in Fock space coupled cluster to a file for post processing. Can be used with external code of Andrei Zaitsevskii (St. Petersburg).

• Restart for RELCCSD. Contributor: Andre Gomes. See the keyword .RESTART and the section *CCRESTART

• Restored integral screening. Contributor: Hans Jørgen Aagaard Jensen
• POLPRP module + Davidson diagonalizer now parallel. Contributor: Markus Pernpointner

• Fixed errors for quaternion symmetries in 2-electron MO integrals used in CI calculations with GASCIP. It is now possible to do CI calculations with GASCIP for C1 symmetry (i.e. no symmetry).
• Fixed error for parallel complex CI or MCSCF with GASCIP
• Fixed compilation of XCFun on Mac OS X High Sierra.

• Change of final (open shell) orbital energies + SCF cycle modification. Contributors: Hans Jørgen Aagaard Jensen and Trond Saue
• .SKIPEP is now default for KR-MCSCF, new keyword .WITHEP to include e-p rotations

• Added the RPF-4Z and aug-RPF-4Z basis sets for f-elements to the already existing files with sets for s, p and d elements. Deleted the aug-RPF-3Z set as that was not an official set.
• Fixed the p exponents for Na in the dyall 4z basis sets to match the archive. The changes are small so should not significantly affect results.
• Updated basis_dalton/ with basis set updates in the Dalton distribution:
  • fix of errors in Ahlrichs-pVDZ (several diffuse exponents were a factor 10 too big)
  • fix of errors for 2. row atoms in aug-cc-pCV5Z
  • added many atoms to aug-cc-PVTZ_J
  • added many Frank Jensen “pc” type basis sets
  • added Turbomole “def2” type basis sets

• RELCCSD expectation values. For more information, see J. Chem. Phys. 145 (2016) 184107 as well as test/cc_gradient for an example.
• Improved start potential for SCF: sum of atomic LDA potentials, generated by GRASP.

• Negative denominators (e.g. appearing in core ionized systems) accepted in RELCCSD
• AOFOCK is now default if at least 25 MPI nodes (parallelizes better than SOFOCK). And .AOFOCK documented.

• Error corrections and updates in isotope properties for the following atoms:
  • Br isotope 2: quadrupole moment .2620 → .2615
  • Ag isotope 2: magnetic moment .130563 → -.130691 (note sign change)
  • In isotope 2: quadrupole moment .790 → .799
  • Nd magnetic moments of isotopes 4 and 5 were interchanged: -0.065 → -1.065 and -1.065 → -0.065
  • Gd: quadrupole moments of isotopes 4 and 5 updated: 1.36 → 1.35 and 1.30 → 1.27
  • Ho isotope 1: quadrupole moment updated 3.49 → 3.58
  • Lu isotope 2: quadrupole moment updtaed 4.92 → 4.97
  • Hf isotope 1: mass was real*4, not real*8, thus 7 digits instead of 179.9465457D0 (i.e. approx 179.9465)
  • Ta isotope 1: quadrupole moment added 0.00 → 3,17
  • Tl isotope 1: nuclear moment 1.63831461D0 → 1.63821461D0 (typo, error 1.d-4)
  • Pb isotope 3: nuclear moment 0.582583D0 → 0.592583D0 (typo, error 1.d-2)
  • Po isotope 1: nuclear moment added: 0.000 → 0.688
• For other bug fixes compared to DIRAC15 we refer to CHANGELOG.rst in the main directory of the Dirac distribution.

• FanoADC-Stieltjes: Calculation of decay widths of electronic decay processes. For more information see JCP 142, 144106 (2015).
• DIRRCI expectation values, see test/dirrci_property for an example.
• Geometry optimization with xyz input, see test/geo_opt_xyz for an example
• KR-MCSCF: Performance improvements for determinant generation in GASCIP

• Relativistic prolapse-free Gaussian basis sets of quadruple-zeta quality: RPF-4Z, aug-RPF-4Z
  • s- and p-block elements: T. Q. Teodoro, A. B. F. da Silva, and R. L. A. Haiduke, J. Chem. Theory Comput. 10 (2014) 3800
  • d-block elements: T. Q. Teodoro, A. B. F. da Silva, and R. L. A. Haiduke, J. Chem. Theory Comput. 10 (2014) 4761
• ANO-RCC basis:
  • Fixed Carbon basis set (wrong contraction coefficients, see [MOLCAS ANO-RCC](http://www.molcas.org/ANO/).
  • Modified the 3 Th h-functions by replacing them with the 3 Ac h-functions to Th.
• Fixed reading of ANO-RCC and ANO-DK3 basis sets from the included basis set library.

• For open-shell SCF calculations, .OPENFAC = 0.5 by default, as this seems to improve convergence. Final orbital energies are recalculated with .OPENFAC 1.0, for IP interpretation.

• Configuration framework uses [Autocmake](http://autocmake.org).

• Intrinsic Atomic Orbitals (IAOs), as formulated by Gerald Knizia, have been implemented to eliminate the polarization contribution in projection analysis.
• The Polarizable Continuum Model (PCM) is available for the inclusion of solvent effects. For more details, see this paper
• As a byproduct of the PCM implementation, molecular electrostatic potential (MEP) maps are available for 4-component electronic-structure calculations, see this paper
• +Q corrections (size-consistency corrections) for KR-CI calculations
• Extended Hückel method using atomic fragments for SCF start guess (alternative to atomic start)

• Magnetizabilities at the Hartree-Fock level with London atomic orbitals (LAOs)
• Improved output for TDDFT excitation energies (from patch 13.1)
• XML output functionality
• Enhancements to frozen density embedding
• Polarization propagator for 4-C excitations (ADC2 extended)
• Enhancements to X2C: local spin-free and spin-orbit X2C
• Dyall basis sets redefined to reduce linear dependence and conform to basis archive files, including fixes
• Basis sets for 1s, 2s, 2p, 3s, 3p, 3d added to Dyall 2z, Dyall 3z and Dyall 4z sets
• Polarized basis sets for SCF/DFT calculations: Dyall 2zp, 3zp, and 4zp, covering valence and outer core polarization
• Dyall aenz (all-electron) basis sets added, with correlating functions for all shells

• Support for Windows 7/8 with GNU MinGW32/64 suite and native math libraries
• New test script
• Simplified testing using MPI
• Updated math library detection
• Better support for MKL libraries
• Support for Cray
• Support for MPI runs which do not use mpirun

• The pam script sets (unless these variables are set by the user):

 MKL_NUM_THREADS=1
 MKL_DYNAMIC="FALSE"
 OMP_NUM_THREADS=1
 OMP_DYNAMIC="FALSE"

• 2-component relativistic Effective Core Potentials (ECPs)
• London Atomic Orbitals (LAOs) at the DFT level
• Simple magnetic balance for NMR shieldings
• LAO current densities
• Overlap diagnostic for TD-DFT calculations of excitation energies
• Pipek-Mezey localization by trust-region optimization
• Long-range MP2/short-range DFT
• Atomic start guess for SCF calculations
• MP2 natural orbitals
• Complex/Damped DFT response module
• New Lanczos algorithm for relativistic Algebraic Diagrammatic Construction (ADC)

• New input style for RELCC and RELADC
• Changed level shift
• Changed bare nucleus corrections (new parameters)
• New MPI 64/32-interface
• Improved start guess and improved SCF convergence
• Changed open-shell orbital energy definition

• Analytic molecular gradient at the DFT level
• New and fast XC integration
• Functional derivatives using automatic differentiation (XCFun)
• New visualization options
• RKBIMP: MO-coefficients generated using restricted kinetic balance (RKB) can be extended by their unrestricted kinetic balance (UKB) complement, thus providing magnetic balance for response calculations involving external magnetic fields
• New and improved 2c Hamiltonian schemes

• New compilation scheme: configure replaced by CMake mechanism
• New pam script (python)
• Alternative launcher: wrapper.py (python)
• New testing framework based on python (runscript)
• Many static allocation calls replaced by dynamic allocation; in practice this means that you may need less WORK array memory and/or more space for dynamic allocation compared to DIRAC10.

• http://groups.google.com/group/dirac-users

• XC GRID has own input section
• .DHF is now .SCF

• .LVCORR is now default; you can force explicit evaluation of (SS|SS) integrals with .DOSSSS

• Hartree-Fock
• Density Functional Theory
• Kramers-restricted Multi-Configuration Self-Consistent-Field
• Coupled Cluster
• Configuration Interaction
• Moeller-Plesset Perturbation Theory

• 4c Dirac-Coulomb (includes scalar relativistic effects and spin-own-orbit coupling)
• 4c Dirac-Coulomb-Gaunt (only HF; includes also spin-other-orbit coupling)
• 4c spin-free Dirac-Coulomb (scalar relativistic effects only)
• 4c Levy-Leblond (nonrelativistic)
• 2c X2C, the one-step exact two-component Hamiltonian
• 2c BSS, the two-step exact two-component Hamiltonian (= DKH(infinity,0))
• 2c molecular-mean-field (= X2Cmmf), X2C transformation with the converged 4c-Fock operator as defining Hamiltonian

• Up to quadratic response properties at the HF and DFT level
• First-order properties with MP2
• Core excitation energies in the static exchange (STEX) approximation
• Ionization energies at the ADC(3) level of theory
• Selected first-order properties with CI

• Full symmetry handling for linear molecules (otherwise up to D2h)
• Parallelization using MPI library calls (MPI should be pre-installed)

• Kramers-restricted MCSCF
• RELADC for correlated calculations of single/double ionization spectra
• large-scale parallel CI (LUCITA/KRCI)
• intermediate Hamiltonian formalism for Fock-space CCSD
• interface to MRCC
• frozen density embedding

• 2c X2C+AMFI for 2-electron spin-orbit corrections (spin-same orbit[SSO]/spin other-orbit[SOO])

• HF/KS excitation energies
• KS response with noncollinear spin polarization and full derivative of functionals
• linear response functions at imaginary frequencies
• more efficient KS DFT code
• London orbitals for HF NMR shieldings

• visualization of unperturbed and perturbed densities
• projection analysis of expectation values
• expectation values/transition moments KRCI/GOSCI

• Hartree-Fock
• Density Functional Theory
• Coupled Cluster
• Configuration Interaction
• Second order Moller-Plesset Perturbation Theory

• 4c Dirac-Coulomb (includes scalar relativistic effects and spin-own-orbit coupling)
• 4c Dirac-Coulomb-Gaunt (includes also spin-other-orbit coupling) (only HF)
• 4c spin-free Dirac-Coulomb (scalar relativistic effects only)
• 4c Levy-Leblond (nonrelativistic)
• 2c X2C, the one-step exact two-component Hamiltonian
• 2c BSS, the two-step exact two-component Hamiltonian (= DKH(infinity,0))

• Up to quadratic response properties at the Hartree-Fock and DFT level
• First order properties with MP2
• Core excitation energies in the static exchange (STEX) approximation.
• Single/Double Ionization energies and spectra at the ADC(3)/ADC(2x) level of theory.

• Full symmetry handling for linear molecules (otherwise up to D2h)
• Parallelization using MPI library calls (MPI should be preinstalled)

• A one-step exact two-component Hamiltonian (X2C)
• Relativistic Green's function (propagator) module RELADC for the calculation of ionization energies
• Possibility to include the Gaunt interaction in HF calculations
• Implementation of several new density functionals
• Linear and quadratic response DFT
• Addition of the latest Dyall basis sets and more non-relativistic basis sets to the basis library
• Analysis by means of fragment orbitals
• New parallelization of the MOLTRA module with reduced I/O
• Parallelization of the LUCITA CI module