One, two and three-dimensional periodic boundary conditions (PBC).
Density fitting a for pure DFT calculations. Support for density basis sets has been added to various basis set keywords. Density basis sets can also be generated automatically.
Analytic molecular mechanics frequencies.
Generalized molecular mechanics force fields and a standalone MM program.
New SCF convergence algorithm (EDIIS + CDIIS).
Restricted active space (RAS) CASSCF calculations.
Analytic CCSD gradients.
Douglas-Kroll-Hess scalar relativistic Hamiltonian (Int=DKH).
SAC-CI energies and gradients.
GIAO magnetic susceptibilities (NMR).
Spin-spin coupling constants (NMR=SpinSpin).
Electronic circular dichroism (ECD) rotation strengths (TD).
Vibration-rotation coupling (Freq=VibRot).
Anharmonic vibration and vibration-rotation coupling via perturbation theory (Freq=Anharm).
Frequency-dependent polarizabilities and hyperpolarizabilities (Polar CPHF=RdFreq).
Hyperfine spectra tensors (Output=Pickett).
Analytic PCM frequencies (SCRF).
Solvent effects on vibrational spectra, NMR, and other properties and for excited states and ADMP calculations.
ONIOM microiterations for large systems, with mechanical or electronic embedding
Electronic embedding for ONIOM(MO:MM) calculations.
The G3 method and variations (G3).
The W1 method and a variation (see W1U).
The CIS(D) excited states method.
The extended Huckel method is now available (Huckel).
NBO orbitals can now be saved for later use in visualization programs and subsequent jobs such as CASSCF calculations (Pop=SaveNBOs).
Additional DFT functionals: OPTX, PBE, B95, B1, B98, B97-1, B97-2, VSXC, HCTH
Additional basis sets: UGBS, MTSmall, DGDZVP, DGTZVP
Additional frozen core options are now available (see FC).
The FMM facility is now automated and does not need to be enabled by the user.
O(N) exact exchange for Hartree-Fock and hybrid DFT.
CASSCF active spaces of up to 14 orbitals for energies and optimizations.
Quadratic coupled algorithm and microiterations for ONIOM(MO:MM) optimizations.
Coulomb engine for pure DFT calculations.
Guess=Read works with ONIOM and Counterpoise.
Enhanced PCM facility (SCRF).
The default initial guess has changed to use the Harris guess (see Guess).
Fundamental physical constants have been updated to the latest values (see Constants).
Both SCRF and SCRF=PCM now default to SCRF=IEFPCM.
Isotopes are now specified as part of the molecule specification.
The temperature, pressure and frequency scale factor for thermochemistry analysis are now specified using the Temperature, Pressure and Scale keywords.
By default, the orbitals displayed during population analysis after semi-empirical calculations are the orbitals resulting directly from the calculation. In Gaussian 98, these were considered to be orbitals over symmetrically orthogonalized AOs and converted back to AOs (multiplying by S-1/2) before display. IOp(4/24=1) can be used to request the previous treatment.
CBS extrapolation uses localization based on populations in minimal basis as the default scheme (see CBSExtrapolate).
The CBS-4 model chemistry has also been updated with both the new localization procedure and improved empirical parameters. The keyword name has changed to CBS-4M to reflect this change.
Counterpoise calculations are now performed with the Counterpoise keyword.