With the release of ORCA 4.1, they have moved our forum and download site to a new server at the Max Planck Institute fuer Kohlenforschung, where the ORCA team now has its home base. Now at https://orcaforum.kofo.mpg.de.

ORCAis an ab initio quantum chemistry program package that contains modern electronic structure methods including density functional theory, many-body perturbation, coupled cluster, multireference methods, and semi-empirical quantum chemistry methods. Its main field of application is larger molecules, transition metal complexes, and their spectroscopic properties. DOI.

List of new features for ORCA 4.1:

SCF/DFT

• B97M-V, wB97M-V, wB97X-V plus various D3 variants of B97 functionals
• Simple input keywords for DSD-BLYP, DSD-PBEP86, and DSD-PBEB95
• CPCM analytic Hessian
• DLPNO-double hybrid DFT including gradient
• SymRelax option in %method

Semiempirical methods

• XTB method of Grimme et al.

Coupled cluster

• Iterative solution of the full (T) equations for DLPNO-CCSD(T)
• Open shell DLPNO-CCSD density and spin density matrices
• Full DLPNO-MP2 gradient
• CIM (Cluster in molecules) Implementation with MP2, CCSD(T), DLPNO-MP2 and DLPNO-CCSD(T)
• IP and EA coupled cluster methods and their DLPNO variants
• STEOM-CCSD for open shells
• SOC between bt-PNO-STEOM and STEOM states
• Improved Multilevel implementation including multilevel DLPNO-IP
• F12-Triples scaling for RHF canonical CCSD(T) based on the CCSD/ CCSD-F12 ratio

Multireference

• New CASSCF SuperCIPT converger is reliable and efficient.
• New options for final orbitals to find partner orbitals for the chosen active space e.g. bonding / anti-bonding partners.
• MC-RPA (Multiconfigurational random phase approximation)
• ◦ AO driven integral direct for calculations on larger molecules
• ◦ Fock matrix -> conventional, direct, RIJ/COSX
• ◦ MPI parallel
• ◦ NTOs for visualizing transitions
• Checking stability of state specific CASSCF wave functions by orca_mcrpa
• Dynamic correlation dressed (DCD-CAS) method with inclusion of relativistic effects (SOC, spin-spin, magnetic fields)
• CASSCF RIJCOSX allows two separate auxiliary basis sets
• CASCI/NEVPT2 protocol for XAS and RIXS

Optimization

• Nudge elastic band method to locate transition states
• Enabled 3-dimensional relaxed potential energy surface scan
• Improvement of redundandant internal coordinate generation
• Faster and more smooth convergence for 3-dimensional systems and embedded cluster models
• Intrinsic reaction coordinate (IRC) following
• Swart model Hessian (good for weak interactions)

Molecular Dynamics

• MD simulations can now use Cartesian, distance, angle, and dihedral angle constraints.
• The MD module now features cells of several geometries (cube, orthorhombic, parallelepiped, sphere, ellipsoid), which can help to keep the system inside of a well-defined volume.
• The cells can be defined as elastic, such that their size adapts to the system. This enables to run simulations under constant pressure.
• Ability to define regions (subsets of atoms) enables applications such as thermostating different parts of the system to different temperatures (cold solute in hot solvent, temperature gradients, ...)
• Trajectories can now be written in XYZ and PDF file format.
• A restart file is written in every simulation step. Simulations can be restarted to seamlessly continue.
• The energy drift of the simulation is now displayed in every step.
• The MD module now works with a broader range of methods (semiempirics, ECPs, QM/MM).
• Fixed a bug in the time integration of the equations of motion which compromised energy conservation.

Spectroscopic properties

• orca_pnmr module tool to calculate paramagnetic NMR spectra
• NMR chemical shifts with RI-MP2 and double hybrid DFT including GIAO’s, spin-component scaling and CPCM
• NMR Spin-Spin coupling in calculations with DFT/HF
• NMR wth ZORA
• Maximoff-Scuseria correction for the kinetic energy density in GIAO-based calculations with meta-GGA functionals
• Exact and gauge invariant transition moments and approximate decomposition into dipole, quadrupole etc terms in all modules.
• PNO-ROCIS method for more efficient X-ray absorption calculations
• IP-ROCISD for high spin ROHF references
• TD-DFT:
• Transient spectra (excited state absorption) for CIS/TDA
• Triplet gradients (with RIJ, COSX and all) for all cases.
• Spin orbit coupling (including CPCM) and gradients
• Root following scheme for optimization
• Slow term to correct energy of relaxed excited state
• Full TD-DFT with double hybrids
• ESD module to calculate spectroscopic properties
• Vibrationally resolved absorption spectra including Duschinsky rotation and/or vibronic coupling.
• Fluorescence and Phosphorescence rates with same options.
• Resonance Raman spectra with the same options
• works with CIS/TDDFT, ROCIS, CASSCF and EOM/STEOM.
• Seven different schemes for obtaining an excited state PES and five different choices of coordinate systems

Analysis tools:

• Open Shell LED
• Dispersion interaction Density plots
• LED for DLPNO-MP2
• LED for the frozen state
• Update of AIM interface
• NBO 7 compatibility (i4)
• Miscellaneous
• Compound method (Infrastructure, plus W2.2, W1, G2(MP2), G2(MP2-SVP), G2(MP2-SV) methods)
• Property file (additional properties, plus new infrastructure)
• Decomposition of correlation energy for canonical RHF CCSD energies to singlet - triple pairs
• Additional EP2 extrapolation schemes using RI-MP2 and DLPNO-MP2 methods as cheap methods (request from forum)
• Lanthanide new def2 basis sets
• def2-XVP/C auxiliary basis sets for Ce-Lu by Chmela and Harding.
• Robust Second order optimizer for localized orbitals
• Added a few basis sets.