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ORCA Version 4.1 released


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

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:


  • 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


  • 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


  • 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.

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