DFT AND TDDFT EXCHANGE-CORRELATION FUNCTIONALS
A large set of innovative functionals and algorithms for
ground, excited, and ionized states, including:
- Dispersion Corrections:
- Becke-Johnson XDM model
- DF-04, VV09, VV10 van der Waals
- DFT-D3 long-range corrections
- General Purpose Functionals:
- M11 and M11-L hybrid meta GGAs
- Becke-05 nondynamic correlation model
- MCY2 hyper-GGA functional of Yang et al
- Double Hybrid Density Functionals
- XYG3 and XYG3-OS double hybrids
- wB97X-2 double hybrid
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New functionals yield smaller errors in the barrier heights for HTBH38/04 reactions than B3LYP. |
POST HARTREE-FOCK FEATURES
- Coupled-Cluster, Equation-of-Motion, and Adiabatic Diagrammatic Construction Methods:
- Significantly enhanced coupled-cluster codes rewritten for better performance on multicore systems
- Energy, gradient, and properties for CCSD, EOM-EE/SF/IP/EA-CCSD
- New EOM methods (2SF, DIP) and triples corrections for chemical accuracy
- New Approaches for Strong Correlation:
- Perfect quadruples and perfect hextuples methods for strong correlation problems
- Coupled Cluster Valence Bond (CCVB) and related methods for multiple bond breaking
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EXCITED STATES AND OPEN-SHELL SPECIES
- EOM-CC Methods for Excited (EE), Ionized/Electron-Attached (IP/EA), and Diradical States (SF, DIP)
- Analytical gradients, multicore parallelization, interface with Effective Fragment Potential Method
- ADC Family of Methods Including ADC(2X)
- RI-SOS-CIS(D): N^4 Excited State Method
- Restricted Active Space Double SF Method for Polyradicals and
Multiple Bond Breaking
- Non-Collinear SF-DFT (improved accuracy for multi-configurational species)
- Analytical Gradient and Hessian for TDDFT/TDA and Full TDDFT
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PROPERTY ANALYSIS
- Energy Decomposition Analysis Based on Absolutely Localized MO's
- Interaction energy between fragments is divided into frozen density (Coulomb + exchange), polarization, and charge-transfer terms.
- In organometallic compunds, it shows the electron donation from ligand to metal (above left) and back donation from metal to ligand (above right).
- Electron Transfer and Excitation Energy Transfer
- CDFT leads to charge-constrained states. CDFT-CI describes configuration interaction among these constrained states.
- Direct coupling method, in its ‘1+1’ version, uses the product of fragment wavefunctions to compute the coupling.
- Fragment charge (or excitation or spin) difference methods compute ET and EET couplings between eigenstates.
- Diabatization schemes, overlap analysis
- Fast NMR Shifts Calculations (made possible with advanced solvers of reponse equations) and Much More.
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The analysis shows the electron donation
from ligand to metal (above left) and back donation from metal to ligand. |
OPTIMIZATIONS, REACTION PATH, VIBRATIONAL ANALYSIS AND SIMULATION
- Automated Reaction Path Finding
- Freezing and Growing String methods
- Local Vibrational Modes with Partial Hessian Vibrational Analysis
- Tunneling and Anharmonic Effects
- Path integral Monte Carlo simulates both electronic and nuclear motions with quantum mechanics
- Simulating IR and Photoelectron Spectra
- Quasiclassical trajectories AIMD by incorporating vibrational zero-point energies into intial velocities
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ENVIRONMENTAL EFFECTS: SOLVATION MODELS, EFP AND QM/MM
- Popular Solvent Models Describing Implicit Solvation Effects
- SM8, COSMO, C-PCM, SS(V)PE, IEF-PCM, and more
- C-PCM/SIWG with smooth potential energy surfaces
- Effective Fragment Potential Method Explicit Solvent Molecules Such as Water
- For both the ground and excited states
- Interfaced with DFT and wave-function based methods
- Unique feature: Built-in library of standard effective fragments
- QM/MM Methods Treating Environment Atoms as Classical Potential
- Internal QM/MM for ground and excited states calculations
- Q-Chem’s unique Yin-Yang atom interface for QM/MM
- Integration with PCM models (QC/MM/PCM)
- External interface with CHARMM for full QM/MM hessian (or its mobile-block-hessian approximation), which allows studying vibrational entropic effects or large-scale conformational changes
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EFP used to compute ionization energies
and redox potentials of bulk-solvated species.
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COMPUTATIONAL EFFICIENCY
- Fast Algorithms for DFT Calculations
- Algorithms for Coulomb (Continuous Fast Multipole Method, J engine, Fourier Transform Coulomb, Quantum Ewald Mesh)
- Algorithms for Hartree-Fock exchange (LinK, ARI-K) and numerical integration (mrXC).
- Perturbation Theory Calculations
- Fast integral transformations, Resolution-of-Identity approximation, scaling of different spin components, Laplace transform, dual-basis extrapolation, and the use of localized orbitals.
- Coupled-Cluster Calculations
- Enhanced by a modern tensor library, Resolution-of-Identity approximation, and Cholesky decomposition.
- Efficient Implementation on Shared-Memory Multicore Machines and Computer Clusters
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PCBM,
phenyl-C -butyric
acid methyl ester 1106 basis functions |
Methylated Uracyl/Water,
CCSD calculation
302 basis functions |
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