Q-CHEM與當前量子化學計算領域內最先進的理論和計算方法結合得非常緊密，因此在該程序中實現了很多其他程序包尚未採用的方法和理論。目前，在Q-CHEM3.0版實現的功能和方法主要有以下幾點：

大分子密度泛函計算的高效算法：
包括新的更有效J矩陣計算方法、線性級別的交換能和力場的計算、使用CFMM（Continuous Fast Multipole Method）方法來產生線性級別的庫侖交換勢
（可用於計算能量和梯度）以及線性級別的密度泛函交換相關能積分的求解等。

局域密度泛函函數、梯度校正密度泛函函數和混合密度泛函函數：
包括Slater 、Becke、GGA91和Gill‘96交換泛函；VWN、PZ81、Wigner、Perdew86、LYP和G G A 9 1 相 關 能 泛 函 ； E D F 1 交 換 相 關 能 泛 函 ；B3LYP、B3P和用戶可定義的混合泛函；解析梯度和解析頻率計算；SG-0標準積分求解網格；可擴展到5294個點的Lebedev網格等。

高階波函數型電子相關能方法：
包括高效半直接MP2能量和梯度的計算；MP3、MP4、QCISD和CCSD能量計算；OD和QCCD能量和解析梯度計算；三重激發校正（QCISD(T)、CCSD(T)和OD(T)能量）；CCSD（2）和OD（2）能量計算；活性空間耦合簇方法：VOD、VQCCD、VOD（2）；局域二階Moller-Plesset（MP2）方法；實電子定義的改進以用於相關能的計算等。
 
廣泛的激發態計算；
包括CIS能量、解析梯度和解析頻率的計算；CIS（D）能量的計算；TDDFT能量計算；耦合簇方法激發態能量計算；耦合簇方法激發態幾何優化；耦合簇方法性質的計算；CCSD和TDDFT的激發態自旋翻轉模型計算等。
 
高性能幾何和過渡態結構優化：
包括通過笛卡爾坐標、Z矩陣坐標、內部相對坐標的優化；固定鍵角、二面角或平面夾角；笛卡爾坐標中原子的固定；初始結構不需要體現出這些所希望的固定值；固定點電荷的幾何優化；內部反應坐標（反應路徑）的計算等；

分子性質的估算和可視化：
包括Onsager、SS(V)PE和Langevin偶極溶劑模型；通過立方體估算密度、靜電勢和軌道；自然鍵軌道（NBO）分析；用CIS和TDDFT計算激發態吸收與解離密度；在估算原子核坐標Hessian量後的震動分析；頻率計算的同位素取代；NMR化學位移；分子中的原子，利用免費的AIMPAC進行AIM分析；SCF波函數的穩定性分析；分子中庫侖能和交換能的位置和動量的計算等；
 
靈活的基組和有效核勢功能：
包括內聯的大量基組和有效核勢；基組超位點錯誤的校正；支持混合以及用戶自定義基組；用於能量和梯度計算的有效核勢；特別高效的基於PRISM的算法，用於計算有效核勢的矩陣元素；用於計算頻率的更快更準確的有效核勢的二階導數等。

另外，Q-CHEM還擁有下列一些專有的功能和特點：
 
COLD PRISM方法：這個方法是最新的用於計算兩電子積分的算法，同時Q-CHEM也採用這個方法來高效率的計算與有效核勢相關的矩陣元素。

Continuous Fast Multipole Method (CFMM)：這個方法使得Q-CHEM能夠用比別的程序更少的時間來計算電子的庫侖相互作用，而且分子越大，節省的時間越多；此外，Q-CHEM也改進了短程相互作用的處理，極大的加速了能量的計算以及力的計算，而且計算精度也沒有損失。

並行計算：Q-CHEM中的並行是採用MPI來實現的。目前在這個軟體中，只有HF、DFT方法以及它們的二階導數實現了並行。但它對解析和數值積分的計算採用的動態負載均衡的辦法，並且在求解偶合擾動SCF方程中採用全域內存使用共享的方式，使得它能夠利用並行計算機的分佈內存進行大結構的頻率計算。

局域MP2方法：Q-CHEM的局域MP2方法是別的程序所沒有的。與其他的局域相關能方法不同，這個方法能夠滿足理論模型化學的所有性質，能夠嚴格地產生連續的勢能面。與傳統地MP2方法相比，這個方法能夠減少硬盤空間的需求，在工作站上可以使用1000-1500個基組函數進行計算。
 
高階耦合簇方法：除了傳統的Q C I S D、CCSD和CCSD(T)方法，Q-CHEM還採用了新的軌道優化耦合簇方法OD等；此外，Q-CHEM採用了新的高階耦合簇方法：CCSD（2）和OD（2），這些方法
在處理化學鍵斷裂和自由基問題上比傳統的QCISD（T）和CCSD(T)要好；另外，Q-CHEM也能夠用耦合簇方法計算激發態，其中的EOM-SF-CCSD、EOMIP-CCSD和EOM-EA-CCSD可以很方便的把Multi Reference問題處理成Single Reference問題，極大簡化了多自由基問題的計算；Q-CHEM對高階耦合簇方法的基態和激發態計算還提供了解析梯度，可用於激發態和基態的幾何優化。
 
連續溶劑模型：包括球形空穴Onsager反應場模型、Langevin水溶劑偶極模型以及極化連續溶劑模型；球形空穴Onsager反應場模型可以使用解析的SCF梯度、可以包括更高階的多極、可以處理包括可溶性鹽的溶劑；極化連續溶劑模型可通過HF和DFT計算來獲得自洽的反應場能量。
 
幾何優化：Q-CHEM結合了Jon Baker的最新版的幾何優化程序包，它包含一套最先進的幾何優化算法。同時，Q-CHEM中的幾何優化程序包還支持內部反應坐標，可用於研究反應路徑。

PARTAN：Q-CHEM是化學計算可視化軟體SPARTAN（www.wavefun.com）的後臺計算程序。SPARTAN可安裝到Windows、Linux、Macintosh、I RI X等操作系統上，它以波函數的圖形界面為前端，以Q-CHEM為後端計算程序，可以很方便的實現分子設計、計算和結果可視化等的一系列流程。
 

Density Functional Theory

• Local Functionals and Gradient-Corrected Functionals
  • Exchange Functionals
    • Slater
    • Beckee '88 (B)
    • GGA91 (Perdew '91, PW91)
    • Gill '96
    • Gilbert and Gill '99 (GG99)
    • Handy and Cohen's OPTX (HC_OPTX)
  • Correlation Functionals
    • VWN (#5 parameterization)
    • Lee-Yang-Parr (LYP), LYP (EDF1 parameterization)
    • Perdew-Zunger '81 (PZ81)
    • Perdew '86 (P86)
    • Wigner
    • GGA91 (Perdew '91, PW91)
  • exchange-correlation functionals
    • EDF1 and Becke(EDF1)
    • PBE functionals
    • SOGGA, SOGGA11 family of GGA functionals
• Hybrid HF-GGA Functionals
  • B3LYP, B3PW91, B3LYP5 
  • (using the VWN5 functional)
  • SOGGA11-X
  • User-definable hybrid functionals
• Meta GGA Functionals
  • M06-L,M11-L
  • PK06, BR89, B94
  • TPSS
• Hybrid Meta GGA and Hyper-GGA Functionals
  • BMK
  • MPW1B95, MPWB1K, PW6B95, PWB6K, M05, M05-2X, M06, M06-2X, M06-HF, M08, M11
  • B3tLap
  • BR89BR94hyb
  • TPSSh
  • RI-B05 for nondynamic correlation
• Double-Hybrid Functionals
  • ωB97X-2
  • XYG3,XYGJ-OS
  • B2PLYP-D
• Long-range corrected (LRC) functionals
  • Long-range corrections from Herbert group: LRC-ωPBEPBE, LRC-ωPBEhPBE
  • Baer-Neuhauser-Livshits (BNL) functional
  • ωB97, ωB97X and ωB97X-D functionals
  • CAM-B3LYP
• Dispersion corrections to DFT
  • Becke and Johnson’s XDM model
  • vdw-DF-04 of Langreth, Lundqvist and co-workers’
  • VV09
  • -D2 and -D3 of Grimme's
  • B97-D
  • ωB97X-D
• Constrained DFT
  • Calculation of reactions with configuration interactions of charge-constrained states with constrained DFT
• User-Definable Linear Combination of Functionals
• Numerical-Grid Based Numerical Quadrature Schemes
  • The SG-0 standard grid
    • This grid is derived from a MultiExp-Lebedev-(23,170), (i.e. 23 radial points and 170 angular points per radial point). This grid was pruned whilst ensuring the error in the computed exchange energies for the atoms and a selection of small molecules was less than 10 microhartree from that computed using a very large grid.
  • The SG-1 standard grid
    • This grid is derived from a Euler-Maclaurin-Lebedev-(50,194) grid (i.e., 50 radial points, and 194 angular points per radial point). 
      This grid has been found to give numerical integration errors of the order of 0.2 kcal/mol for medium-sized molecules, including particularly demanding test cases such as isomerization energies of alkanes.
  • Lebedev and Gauss-Legendre Angular Quadrature Schemes
    • Lebedev Spheres avaiable for up to 5294 angular points.
  • Incremental Density Function Theory
    • Improves efficiency of DFT calculations by greater amounts as convergence is reached by use of the difference denisty and Fock matrices.
• Analytical First Derivatives for Geometry Optimizations
• Analytical Second Derivatives for Harmonic Frequency Analysis
• Inclusion of the first and second derivatives 
• of the Becke Weighting Functions for 
• greater accuracy.
• Near-edge X-ray absorption with short-range corrected DFT

Linear Scaling Methods

• Fast numerical integration of exchange-correlation with mrXC (multiresolution exchange-correlation)
  • Treats the smooth and compact parts of the electron density separately
  • Highly efficient, no errors
• Fourier Transform Coulomb Method (FTC)
• Continuous Fast Multipole Method (CFMM)
  • Fastest ab initio implementation of multipole-based methods
  • Linear-cost calculation of electronic Coulomb interactions
  • Finds exact Coulomb energy; no approximations are made
  • Efficiently calculates energy and gradient
• Linear-Scaling HF-exchange method (LinK)
  • Linear scaling exchange energies and gradients for cases with sparse density matrices
• Resolution-Identity
  • Faster DFT and HF calculations with atomic resolution of the identity (ART) algorithms
• Dual Basis
  • Fast calculation with one iteration only with the large basis basis
  • Accurate in relative energy
  • Applicable to DFT and MP2
• Linear Scaling Grid Based Integration for Exchange-Correlation Functional Evaluation
  • Efficient computation of the exchange-correlation part of the dual basis DFT
  • Fast DFT calculation with ‘triple jumps’ between different sizes of basis set and grid and different levels of functional
• Linear Scaling NMR Chemical Shifts 

 Q-Chem's AOINTS Package for Two Electron Integrals

• Incorporates the latest advances in high performance integrals technology
• COLD PRISM
  • The most efficient method available for evaluation of two-electron Gaussian integrals
  • Algorithms choose the optimum method for each integral given the angular momentum and degree of contraction
  • Analytical solution of integrals over pseudopotential operators
• J Matrix engine
  • Direct computation of Coulomb matrix elements approximately 10 times faster than explicit integral evaluation

SCF Improvements

• Automated optimal hybrid of in-core and direct 
• SCF methods
• Direct Inversion in the Iterative Subspace (DIIS)
  • Drastically reduces the number of iterations necessary to converge the SCF
• Initial Guessing Schemes
  • Improves the initial starting point for the SCF procedure
  • Superposing spherical averaged atomic densities (SAD)
  • Generalized Wolfsberg-Helmholtz (GWH)
  • Projection from smaller basis sets
  • Core Hamiltonian Guessing
• Stability Analysis for SCF Wavefunctions
  • Tests for a complex solution to the SCF equations to ensure the quality of energy minima.
  • Available for restricted and unrestriced HF or DFT wavefunctions.
• Maximum Overlap Method (MOM)
  • Prevents oscillation of the occupations at each iteration that can hinder convergence
  • Scales cubic with the number of orbitals
• Direct Minimization of the Fock Matrix
  • Follows the energy gradients to minimize the SCF energy providing a useful alternative to DIIS
• Relaxed constraint algorithm (RCA) for converging SCF
• Intermediate molecular-optimized minimal basis of polarized atomic orbitals PAOs)
  • Set of orbitals defined by a atom-blocked linear transformation from the fixed atomic orbital basis
  • Potential computational advantages for local MP2 compuations
  • Analytical gradients and second-order corrections to the energy available 

Møller-Plesset Theory

• Second-Order Møller-Plesset Theory (MP2)
  • Restricted, Unrestricted, and Restriced Open-Shell Formulations Available
  • Energy via direct and semi-direct methods
  • Analytical gradient via efficient semi-direct method available for restricted and unrestricted formalisms
  • Proper treatment of frozen orbitals in analytical gradient Energy via MP3, MP4 and MP4SDQ methods also available
• Local MP2 Methods
  • Drastically reduces cost through physically motivated truncations of the full MP2 energy expression
  • Reduces the scaling of the computation with molecular size
    • Capable of performing MP2 computations on molecules roughly twice the size as capable with standard MP2 without significant loss of accuracy!
  • Utilizes extrapolated PAO's (EPAO's) for local correlation
  • Available methods are the TRIM (triatomics in molecules) and DIM (diatomics in molecules) techniques
    • Yields contiuous potential energy surfaces
    • TRIM recovers around 99.7% of the full MP2 energy
    • DIM recovers around 95% of the full MP2 energy
• RI-MP2 Methods
  • Up to 10 times faster for MP2 and Local MP2
• Dual-basis RIMP2 methods
• Opposite-spin MP2 methods
  • Scaled opposite-spin MP2 method (SOS-MP2)
  • Modified opposite-spin MP2 method (MOS-MP2)
  • Optimized-orbitals opposite-spin MP2 method (O2)
• Attenuated MP2 method 

Coupled-Cluster Methods

• Significantly enhanced coupled-cluster code rewritten for better performance and multicore systems for many modules in 4.0
• Singles and Doubles (CCSD)
  • Energies and gradients are available.
  • Frequenies available via finite differences of forces.
  • RI implementation is available (energies only)
• EOM-XX-CCSD
  • XX = EE, EA, IP, SF (energies and gradients) DIP, 2SF (energies)
  • Robust treatment of radicals, bond-breaking and symmetry- breaking problems
• Non-Iterative Corrections to the Coupled Cluster Energies
  • (T) Triples Corrections (CCSD(T)) for CC energies
  • (2) Triples and Quadruples Corrections (CCSD(2)) for CC energies
  • (dT) and (dF) corrections for CCSD, EOM-SF-CCSD, and EOM-IP-CCSD.
• Extensive use of molecular point group and spin symmetry to improve efficiency.
• Quadratic Coupled-Cluster Doubles
  • Improved behavior of the coupled-cluster wavefunction for such trouble cases as homolytic bond dissociation
• QCISD, QCISD(T) and QCISD(2) energies available
• Frozen Core Approximations, including frozen natural orbitals, available to increase treatable system size
• Interface with EFP is avaliable for treating the effect of the environment
• Dyson orbitals are available
• RI/Cholesky decomposition implementation of CCSD and EOM-CCSD

Valence Space Models for Strong Corrrelation

• Optimized Orbital Coupled-Cluster Doubles (OD)
  • Helpful in avoiding artifactual symmetry 
    breaking problems
  • The mean-field reference orbitals are optimized to minimize the total energy
  • Alternative approach to Brueckner 
    coupled-cluster
  • OD, OD(T), and OD(2) energies and 
    gradients available
• Valence Optimized Orbital Coupled-Cluster
  Doubles (VOD)
  • Coupled-cluster approximation of the traditional CASSCF method.
  • A truncated OD wave function is utilized within a valence active space
  • Requires far less disk space and scales better with system size than CASSCF so that larger systems can be treated
  • VOD, VOD(T), VQCCD and VOD(2) energies and gradients available
• Perfect Quadruples and Perfect Hextuples methods
• Coupled Cluster Valence Bond (CCVB) and related methods for multiple bond breaking
• Extended RAS-nSF for studying excited states 

Supported Calculation Types

• Vertical absorbtion spectrum
  • The calculation of the excited states of the molecule at the ground state geometry, as appropriate for absorption spectroscopy.
• Excited state optimization
  • Analytic gradient available with CIS, TDDFT and EOM-CCSD
• Excited state vibrational analysis
  • Available for UCIS, RCIS and TDDFT
• Collinear and Non-Collinear Spin-Flip DFT 

CIS Methods

• Excited states are computed starting from a 
  Hartree-Fock wavefunction
  • Provides qualitatively correct descriptions of single-electron excited states
  • Geometries and frequencies comparable to ground-state Hartree-Fock results
• Efficient, direct algorithm for computing closed- and open- shell energies, analytical gradients and second derivatives
• CIS (XCIS) Method available
  • Comparible results to the closed-shell CIS method for doublet and quartet states
• CIS(D) and SOS-CIS(D) perturbative doubles correction available
  • Reduces the errors in CIS by a factor of two or more (to roughly that of MP2)
• RI-CIS(D) and RI-CIS(D0) methods for faster correlated excited state calculations 

Time-Dependent DFT (TDDFT)

• Excited state energies computed from a ground state Kohn-Sham wavefunction
• For low-lying valence excited states, TDDFT provides a marked improvement over CIS, at about the same cost
• Provides an implicit representation of correlation effects in excited states
• Provides marked improvement over CIS for low-lying valence excited states of radicals
• Spin-flip density functional threory (SFDFT)
  • Extends TDDFT to states beyond the low-lying valence states.
  • Also useful for bond-breaking processes and radical and diradical systems
• Nuclear gradients of excited states with TDDFT
• Direct coupling of charged states for the study of charge transfer reactions
• Analytical excited-state Hessian in TDDFT within Tamm-Dancoff approximation
• Improved TDDFT prediction with implementation of asymptotically corrected exchange-correlation potential (TDDFT/TDA with LB94)
• Obtaining an excited state self-consistently with MOM (maximum overlap method)
• Overlap analysis of the charge transfer in a excited state with TDDFT (Nick Besley, Section 6.3.2).
• Localizing diabatic states with Boys or Edmiston-Ruedenberg localization scheme for charge or energy transfer
• Implementation of non-collinear formulation extends SF-TDDFT to a broader set of functionals and improves its accuracy 

Wavefunction-Based Correlated Excited State Methods

• Equation of Motion Coupled-Cluster Singles and Doubles EOM-CCSD
  • Method of computing vertical excitation energies via linear response from the ground state CC wavefunction.
• Spin-Flip Excited State Methods
  • Improved treatment of di- and tri-radical systems.
  • Address bond-breaking problems associated with a single-determinant wavefunction.
  • Available for OD and CCSD levels of theory.
• Excited State Property Calculations
  • Transition dipoles and getometry
• Potential energy surface crossing minimization with EOM-CCSD
• Correlated excited states with the perturbation-theory based, size consistent ADC scheme of second order
• Restricted active space spin- flip method for multireference ground states and multi-electron excited states 

 Attachment-Detachment Analysis for Excited States

• A unique tool for visualizing electronic transtions
  • Utilizes the difference density matrix between the ground exctied state to create a one-electron picture of electronic transitions
  • Useful in classifying the character electronic transistion as valence, Rydberg, mixed, or charge-transfer.

Automated Geometry and Transition Structure Optimization

• Uses Dr. Jon Baker's OPTIMIZE package
  • Utilizes redundant internal coordinates to ensure rapid convergence even without an initial force constant matrix
• Geometry Optimization with General Constraints
  • Can impose bond angle, dihedral angle (torsion) or out-of-plane bend constraints Freezes atoms in Cartesian coordinates
  • Desired constraints do not need to be imposed in starting structure
• Optimizes in Cartesian, Z-Matrix or delocalized internal coordinates
• Eigenvector Following (EF) algorithm for minima and transition states
• GDIIS algorithm for minima
  • Greatly speeds up convergence to an equilibrium geometry
• Intrinsic Reaction Coordinates (IRC) following
  • Connect equilibrium geometries and transistion states along reaction paths.
  • Ab initio dynamics with extrapolated z-vector techniques for MP2 and/or dual-basis methods
  • Improved robustness with Version 4.0
• Freezing and Growing String Methods for efficient automatic reaction path finding 

Vibrational Spectra

• Automated with both analytical and numerical second-derivatives
• Infrared and Raman intensities
• Outputs standard statistical thermodynamic information
• Isotropic subsitution available for comparison with experiment
• Anharmonic correction
• Partial hessian analysis
• Exact, quantum mechanical treatment of nuclear motions at equilibrium with path integral methods.
• Calculation of local vibrational modes of interest with partial Hessian vibrational analysis.
• Quasiclassical ab initio molecular dynamics. 

NMR Shielding Tensors

• NMR chemical shifts provides a reliable comparison between the experimentally measured NMR signals and structural properties.
• First and only linear-scaling NMR calculation with hundreds of atoms 

Analysis of Electronic Structures

• NOB 5.0, a sophisticated approach to population analysis
• Stewart Atoms
  • Recovers the atomic identity from a molecular density
  • Provides a simplified representation of the electronic density
  • Q-Chem utilizes the resolution of the identity (RI) for computation of these values.
• Momentum Densities
  • Property that shows what momentum an electron is most likely to possess
  • Useful in comparison to Compton scattering experiment results
  • Complement the normal electron density in providing detailed picture of the electronic structure
• Intracules
  • These are unique 2-electron distribution functions that provide the most detailed information about the Coulomb and exchange energies in a molecule with respect to position and momentum
  • Analytical Wigner Intracule
• Atoms in Molecules Analysis (AIMPAC)
  • Q-Chem can now produce output suitable for use by the AIMPAC program, which is a freely available program that performs AIM analysis.
  • AIMPAC is available at www.chemistry.mcmaster.ca/aimpac/imagemap/imagemap.htm
• Hirshfeld population analysis
• Localized atomic magnetic moments and correlated bond orders within DFT
• T-Chem: Quantum transport properties via the Landauer approximation

Solvation Modeling

• The simple Onsager reaction field model
• The Langevin dipoles model
  • Continuum model that realistically treats solvation effects by adding a layer of dipoles around the Van der Waals surface of the solute
• SS(V)PE: a new dielectric continuum model
• SM8 solvation model
• Smooth solvation energy surface with switching/Gaussian polarizable continuum medium PCM) solvation models for QM and QM/MM calculations.
• The original COSMO solvation model by Klamt and Schüürmann with DFT energy and gradient. 

Relativistic Energy Corrections

• Additive correction to the Hartree-Fock energy is computed atomatically everytime a frequency calculation is requested
  • Needed for an accurate description of heavy-atoms
  • Approximately accounts for the increase of electron mass as the electron approaches the speed of light
  • Based on Dirac-Fock theory 

Diagonal Adiabatic Correction

• Computes the Born-Oppenheimer diagonal correction in order to account for a breakdown in the adiabatic separation of nuclear and electronic motions

 Intermolecular Interaction Analysis

• SCF with absolutely localized molecular orbitals for molecular interactions (SCF-MI)
• Roothaan-step (RS) correction following SCF-MI
• Energy decomposition analysis (EDA)
• Complementary occupied-virtual pair (COVP) analysis for charge transfer
• Automated basis-set superposition error (BSSE) calculation
• Symmetry-adapted perturbation theory for intermolecular interaction energy decomposition
• XPol monomer-based SCF calculations of many-body polarization effects

Other Analytical tools

• Analysis of metal oxidation states via localized orbital bonding analysis
• Visualization of noncovalent bonding using Johnson and Yang’s algorithm
• ESP on a grid for transition density 

Gaussian Basis Sets

• strong>Standard Pople Basis Sets
  • 3-21G (H-Cs), 4-31G (H-Cl), 6-31G (H-Kr), and 6-311G (H-Kr)
  • Polarization and diffuse function extensions
• Dunning's systematic sequence of correlation consistent basis sets
  • Obtained from the Pacific Northwest Basis Set Database cc-pVDZ, cc-pVTZ, cc-pVQZ, cc-pV5Z for H-Ar
  • Augmented versions of these sets for H-Ar
  • Core-valence effects included through the cc-pCVXZ basis set for B-Ne
  • DZ and TZ basis sets also available
• The modern Ahlrichs double and triple zeta basis sets are also available
• G3Large basis set for transition metals
• User-specified basis sets supported 

Pseudopotential Basis Sets

• These sets incorporate relativistic effects
• PRISM now supports fully analytical treatment of integrals over pseudopotential operators
• Standard pseudopotential sets obtained from the Pacific Northwest Basis Set Database
• Available sets are:
  • The Hay-Wadt minimal basis
  • The Hay-Wadt valence double zeta basis
  • lanl2dz (mimic of Gaussian's lanl2dz)
  • Stevens-Bausch-Krauss-Jaisen-Cundari-21G
  • CRENBL-Christiansen et al. shape consistent large orbital, small core
  • CRENBS-Christiansen et al. shape consistent small basis, large core
  • Stuggart relativistic large core
  • Stuggart relativistic small core
• User-defined pseudopotential basis sets supported 

Correction for Basis Set Superposition Error (BSSE)

• Places basis functions on ghost atoms to correct the overestimation of binding energies. 

Interface to CHARMM

• YinYang Atom model without linked atoms
• ONIOM model implemented
• The QM/MM interface between Q-Chem and CHARMM is distrib