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Molecular Modeling Methods

Methods: Parameters & Basis Sets

(Accuracy: ΔHf°, ΔHr, ΔH kcal/mole;
D Debye; IP eV; l Å; a,d °; v cm-1)

Method Groupings


Molecular Mechanics Methods



  • MM2 - Molecular Mechanics, Allinger Force Field version 2
Basis:
XRD & ND Structures
75 parameters
3rd Order Dihedral term
bond dipoles vs electrostatic
Pros:
covalent
organic
Ground States
Cons:
metal bonding
excited states
transition states
Atoms:
H, D
B - F
Si - Cl
Ca, Cr, Co, Cu - Br
Sr, Rh, Pd, Cd, Sn, Te, I
Pb
Acc’y:
ΔHf°±0.5, ΔHr±0.4, ΔH±2
D±0.1
l±0.01, a±1, d±8
v±80

  • MM3 -
  • Basis: added 4th order dihedral
    Atoms:
    H
    Li, C - O
    Na, Mg, P, S
    K, Ca
    Rb, Sr, I
    Cs, Ba
    Pros:
    accuracy
    cyclohexylamine conformation
    entropy by vibrational analysis
    F-C-C-F hyperconjugation
    anomeric effect
    Bohlmann effect
    Acc’y:
    ΔHf°±0.6, ΔHr±0.4, ΔH±1
    D±0.07
    l±0.01, a±1, d±5
    v±40

  • ChemX -
  • Basis:
    organics
    inorganics
    peptides
    Acc’y: ΔHr±1, ΔH±2
    • Sybyl -
    Basis:
    biomolecules
    atomic
    general purpose
    harmonic force field
    Pros:
    biomolecules
    saturated HCs
    Cons:
    inorganics
    unsaturations
    nonbond attractions high
    2-Cl-THP eq. (no anomeric)
    Acc’y: ΔHr±1, ΔH±1

    • Amber -
    Basis:
    biomolecules
    harmonic force field
    25 parameters
    united atom charges from HF 6-31G*
    (CH as united atom in old version)
    electrostatic ("disappearing" L-J) H-bond
    Pros:
    proteins/DNA
    aqueous
    Cons:
    inorganic
    no general atom types
    Atoms:
    H
    C - F
    Na, Mg, P - Cl
    K, Ca, Fe, Cu, Br
    Rb, I
    Cs
    Acc’y: ΔHr±0.7

    • CHARMm -
    Basis:
    18 parameter force field
    (CH as united atom in old version)
    Pros:
    biopolymers
    QM-MD
    GAMESS or AMPAC QM
    Atoms:
    H
    C - O
    Na - S
    K - Fe
    Rb
    Eu
    Acc’y:
    ΔH±0.9
    l±0.01, a±1

  • OPLS - Optimized Potentials for Liquid Simulation
  • Basis:
    electrostatic ("disappearing" L-J) H-bond
    protein/DNA
    liquids, solutions
    ab initio calc'ns on 100 organics
    CH as united atom
    Pros: condensed phase

    • Born Model -
    Atoms:
    H
    Li, Be, O
    Na - Si, Cl
    K - Ni, Zn, Ge, Br
    Rb - Nb, Cd, Sn, I
    Cs- La, Nd, Eu-Tb, Ho, Yb-Hf
    Pu

  • Dreiding -
  • Basis:
    Bonds from atomic radii
    angles from hydrides
    harmonic force field
    Pros: General organic & main group
    Cons:
    Accuracy
    nonphysical charges
    2-MeO-THP equilibrium
    Atoms:
    H
    B - F
    Na, Al - Cl
    Ca, Fe, Zn - Br
    In - I
    Acc’y:
    ΔH±2, ΔHr±1
    l±0.03, a±3, d±8

    UFF - Universal Force Field
    Basis:
    Organic
    Inorganic
    parms calc’d from basic props
    Pros: full periodic table
    Cons:
    needs charge equilibration
    2-MeO -THP equatorial
    Acc'y: ΔHr±0.9

    • CFF - Consistent Force Field
    Basis:
    Class II Force Field
    based on ab initio/QM data
    nondiagonal force field
    crossterms
    generalized parameters
    Atoms:
    H
    C-F
    Na, Si-S, Ar
    Ca, Br
    I
    Cons:
    2-MeO-THP equatorial
    nonbond anomaly expands condensed phase
    Acc’y:
    ΔHr±0.5, ΔH±0.8
    l±0.01, a±1
    solubility parameter±0.2
    sorption energy±5

  • PCFF -
  • Basis:
    derived from CFF, QM based FF
    optimized for polymer properties

  • COMPASS - Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies
  • Basis:
    derived from CFF, QM based FF
    optimized for condensed phase MD
    ESP from 6-31G*
    integral for cutoff tail sums
    6-9 L-J term
    Pros:
    long range/nonbonded interaction
    condensed phase properties
    Acc’y:
    ΔHr±0.4
    a±1.8
    Xtal densities +6%

    • CVFF -
    Basis:
    general purpose
    Morse function stretch term
    nondiagonal force field
    crossterms
    empirical parametrization
    Cons: anomeric effect w/ 2-MeOTHP
    Acc'y: ΔHr±1

    • ESFF
    Basis:
    diagonal valence
    rule based:
    electronegativity
    atomic radii
    hardness
    scaling
    d-p π bonding
    organics, inorganic, organometallic & biomolecules
    Pros:
    any element
    organometallic complexes
    Cons: accuracy
    Atoms:
    H
    Li - F
    Na - Cl
    K - Br
    Rb - I
    Cs - At

  • MMFF94 – Merck Molecular Force Field
  • Basis:
    small molecule
    ab initio & experimental
    Pros: ions


    Semiempirical Quantum Mechanics



    (1-Electron MO Methods)


    • Hückel -
    Basis:
    "Tight Binding Approximation"
    π-orbitals only
    Hµµ= alpha
    Hµv = beta, adjacent atoms only
    Sµv = 0
    Pros:
    orbital symmetry
    resonance energy
    back of envelope
    Cons:
    flat, π orbitals only
    polars poor

  • EHT -
  • Basis:
    valence s & p’s
    Hµµ= -IPµ (ionization potential)
    Hµv = 1.75(IPµ + IPv)Sµv
    Sµv computed
    Pros:
    C2H6 rotational barrier
    Woodward-Hoffman rules
    includes AO overlap terms
    Fock matrix diagonalized once
    Frontier orbitals
    Walsh Diagrams
    All elements
    Cons:
    valence only
    geometry poor
    partial charges high
    singlet & triplet same (no e- spin)
    no e-/e- or nuclear repulsions

  • IEHT -
  • Basis:
    Iterate to consistent charge
    Hµµ= -IPµ - Qa(IPa-EAa)
    Pros:
    reasonable, but low charges
    better dipoles
    better orbital order
    Cons:
    valence only
    convergence poor
    benzene asymmetric

  • Fenske-Hall -
  • Basis:
    parameter free
    minimal basis
    all electron
    spectroscopic Slater terms

    (2-Electron MO Methods)


    • CNDO - Complete Neglect of Differential Overlap
    Basis:
    all 2 e- overlap Orbitals
    IP & EA
    XµXvdt = 0
    Hµv ßabSµv fit to minimum basis set
    Pros:
    bond lengths
    bond angles
    Cons: dissociation energies poor
    Acc’y: ΔHf°±200

    • PPP -
    Basis:
    one 2pπ STO per conjugation
    single CI
    valence π & sigma separate
    Pros: aromatic species
    Cons:
    valence only
    ignores many e-/e- repulsions

  • INDO/1 -
  • Basis:
    minimal basis set
    valence s, p, & d orbitals
    2-center integrals 0
    includes 1-center exchange integrals
    Hµµ= -(IPµ - EAµ/2 + . . .
    Hµv from STO-3G SCF
    Pros:
    transition metals
    bond lengths
    bond angles
    singlet-triplet splitting
    better electron spin
    SCRF
    Cons:
    small rings favored
    dye absorbances low
    no double excitations
    dissociation energies poor
    no SCRF for spectra
    Atoms:
    H
    Li - F
    Na - Cl
    K - Zn
    Y - Cd
    Acc’y:
    ΔHf°±100
    l±0.08

  • INDO/S -
  • Basis:
    parameterized for spectra
    single CI
    Pros: UV spectra
    Cons: metals w/ unpaired e-
    Atoms:
    Li, B - F
    P, S
    Sc - Zn

    (2 Electron NDDO Methods)


    • MINDO/3 -
    Basis:
    32 molecule parameterization
    1-center integral parameters
    3 & 4-center integrals on same
    resonance integral from exp.
    Pros:
    carbocations
    amides flat
    Cons:
    valence s & p only
    small rings favored
    resonance energy low
    no H-bonds
    lone pair repulsion low
    rings flat
    transition states poor
    Atoms:
    H
    B - F
    Si - Cl
    Acc’y:
    ΔHf°±5, ΔHr±13
    D±0.5, IP±0.7
    l±0.02

  • MNDO - Minimal Neglect of Differential Overlap
  • Basis: 32 molecule parameterization
    Pros:
    multiple bonds
    EA’s for ions
    better lone pair repulsion
    better angles
    Cons:
    valence s & p only
    no H-bonds, no H2O dimer
    spurious H-H interaction
    S, Cl, & Br IP high
    activation barriers high
    bond dissociation enthalpies low
    conjugation low
    3-center B bonds low
    -O-O- bond ~ 0.17Å short
    C-O-C angle 9° large
    Ar-NO2 out of plane
    amides pyramidal
    no Van der Waals attraction
    steric crowding disfavored:
    neopentane unstable
    4-membered rings too stable
    hypervalent unstable
    Atoms:
    H
    Li - F
    Al - Cl
    Cr, Zn, Ge, Br
    Sn, I
    Hg, Pb
    Acc’y:
    ΔHf°±11, ΔHr±13, ΔHdiss-20, ΔH±16
    D±0.5, IP±0.8
    l±0.07, a±5, d±17
    v+11%

  • MNDO/d -
  • Basis:
    adding d-orbitals to MNDO
    split valence
    11 parameters for sp elements
    15 parameter for spd elements
    d orbitals for 2nd row main group
    Atoms:
    Na - Cl
    Ti, Fe, Ni, Cu, Zn, Ge - Br
    Zr, Pd, Ag, Cd, Sn - I
    Hf, Hg
    Pros:
    Heat of formation
    hypervalent shape
    Cons:
    IP
    dipole moment
    overpredicts agostic interaction
    metal-ethylene short
    no insertion barrier
    Acc’y:
    ΔHf°±6
    D±0.5, IP±0.6
    l±0.06, a±2

  • AM1 - Austin Model 1
  • Basis:
    100 molecule parameterization
    1-center from spectroscopy
    minimal basis set
    Gaussian patches
    7-21 parameters per element
    theoretical consistency
    Pros:
    H-bond energies
    H-bond lengths
    proton affinities
    better activation barriers
    hypervalent P
    Heat of Formation 40% better
    2-Cl-THP axial (anomeric)
    Cons:
    valence s & p only
    no hypervalent compounds
    P orbitals irregular @ 3Å:
    P4O6 asymmetric
    P-O bonds
    conjugate interactions low
    -CH2- ΔHf ~ 2 kcal low each
    Heat of Hydrogenation low
    bond dissociation enthalpies low
    activation enthalpies high
    -NO2 energies high
    -O-O- bond ~ 0.17Å short
    H-bond angles, H2O H-bond geometry wrong
    C-C-O-H gauche in ethanol
    H+ transfer barrier high
    acrolein, glyoxal
    Atoms:
    H
    Li, B - F
    Al - Cl
    Zn, Ge, Br
    I
    Hg
    Acc’y:
    ΔHf°±8, ΔHr±5, ΔHdiss-20, ΔH±7
    D±0.5 ,IP±0.6
    l±0.06, a±4, d±13
    v+4.7%

  • SAM1 -
  • Basis: AM1 w/ d-orbitals
    Pros:
    theoretical consistency
    transition metals
    Atoms:
    H
    C - F
    Si - Cl
    Fe, Cu, Br
    I
    Acc’y:
    ΔHf°±8, ΔHr±5
    D±0.4, IP±0.4
    l±0.04, a±3
    v±13%

  • PM3 -
  • Basis:
    657 molecule parameterization
    minimal basis set
    18 parameters per element
    2 Gaussians for each element
    all 2 e- integral parameters optimized
    Pros:
    hypervalent included
    HOF 40% better
    -NO2 better
    ground state geometries better
    reproducing experimental data
    H2O H-bonds: lengths & angles
    Cons:
    partial charges on N unreliable
    bond dissociation enthalpies low
    amides pyramidal, barrier low
    no barrier to formamide rotation
    spurious minima
    D2d symmetry for CBr4
    CH4 LUMO symmetry A1
    IP’s poor
    Proton Affinity
    H+ transfer barrier high
    wrong glucose geometry:
    H-bonds 0.1Å short
    C-C-O-H gauche in ethanol
    VdW attraction high/H-H core repulsion low, H-H 1.7 vs 2.0 Å
    Atoms:
    H
    Li, Be, C - F
    Mg - Cl
    Zn - Br
    Cd - I
    Hg - Bi
    Acc’y:
    ΔHf°±9, ΔHr±7, ΔHdiss-20, ΔH±9
    D±0.6, IP±0.7
    l±0.05, a±9, d±15
    v±20%

  • PM3(tm) -
  • Basis:
    PM3 with d-orbitals
    minimal basis set
    optimized for geometries
    Pros:
    transition metals
    geometries
    Cons: energies
    Atoms:
    H
    Li - F
    Mg - Cl
    Ca, Ti, Cr - Br
    Zr, Mo, Ru - Pd, Cd - I
    Hf - W, Hg
    Gd



    Density Functional Theory



    Basis: Kohn-Sham theory
    Pros:
    static correlation included
    less basis set sensitivity
    less spin contamination
    Cons:
    no dynamic correlation
    quasiparticle functions, not true MOs
    overstabilizes low spin state of metal complexes

    • Xalpha
    Basis:
    Local Spin Density/functionals
    Slater style exchange
    alpha ~ 0.7
    Pros:
    geometries
    EA's
    Cons:
    no dynamic correlation: VdW/dispersion
    H-bonds
    N2 orbital order
    bond energies high
    IP's low
    bandgap low
    delocalized 3e- bonds too stable
    exchange functional only
    Acc'y:
    l±0.02, a±3
    v±35

  • SVWN -
  • Basis:
    Local Spin Density functionals
    Slater exchange
    Vosko-Wilk-Nusair correlation
    Pros:
    scales as big x n^2
    no parameters
    Cons:
    bonds short
    bond energies high
    proton affinities
    H-bonds
    H-abstractions poor
    radical Rxn barriers low
    long range dispersion
    band gap low
    spurious e- self interaction
    overstablizes lo spin states of metal complexes
    Acc’y:
    ΔHf+90, ΔHr±9, ΔHdiss+16, ΔHatom+80, ΔH±7
    D±0.1
    l±0.02, a±2
    v±7%

  • LYP
  • Basis:
    Lee-Yang-Parr gradient correction
    correlation functional from He atom
    Cons:
    charge transfer complexes
    excited states
    1 e- correlation 0
    nonuniform e- gas limit
    parallel = opposite spin e- pairs

  • P86
  • Basis:
    Perdew gradient correction
    correlation functional
    parameter free
    Pros:
    uniform e- gas limit
    parallel opposite spin pairs
    Cons: 1 e- correlation 0

    • B88
    Basis:
    Becke gradient correction
    exchange functional
    1 parameter fitted to calculated atomic data
    Pros:
    1 e- correlation =0
    parallel opposite spin pairs
    Cons:
    nonuniform e- gas limit
    inhomogeneity limits interpolation

  • BP - Becke-Perdew
  • Basis:
    nonlocal/Generalized Gradient Approximation method
    B88 exchange w/ P86 correlation
    scales as n^3
    Pros:
    transition metals
    better metal spin state preference
    Cons: overstablizes high spin state of metal complexes
    Acc'y:
    ΔHf+16, ΔHr±5, ΔHdiss+5, ΔHatom+20
    D±0.2
    l±0.02, a±0.9

  • BLYP - Becke Lee-Yang-Parr
  • Basis:
    nonlocal/Generalized Gradient Approximation method
    B88 exchange w/ LYP correlation
    scales as n^3
    Pros:
    heavy atom BDE's
    IR scaling
    better metal spin state preference
    Cons:
    popular, well tested/validated
    overstablizes high spin state of metal complexes
    transition states for: F + H2, N + O2, O + HCl
    Acc'y:
    ΔHf±7, ΔHr±5, ΔHdiss±5, ΔHatom±9, ΔH†±6
    D±0.2
    l+0.03, a±1
    v±6%

  • GGA91
  • Pros:
    parallel opposite spin pairs
    uniform e- gas limit
    no fit parameters
    H-bonds
    Cons: 1 e- correlation 0

    • ACM – Adiabatic Correction Method
    Basis:
    nonlocal gradient corrections
    hybrid HF exchange for part of DFT
    Pros:
    transition states
    H-bonds

    • B3LYP -
    Basis:
    hybrid nonlocal method
    3-parameter exchange fitted to G2 thermochemistry data:
    Becke exchange
    HF exchange
    LYP correlation
    favors greater density
    favors greater inhomogeneity
    Pros:
    good rxn barriers
    nondynamic correlation
    radical hyperfine coupling
    eliminates overbinding
    agostic interactions
    transition metal geometries
    transition metal complex spin preferences
    naphthalene cation geometry
    O3 frequencies
    popular, well tested/validated
    Cons:
    bonds slightly long
    no dynamic correlation: dispersion interactions
    transition state for: F + H2
    harder to converge for transition metals
    scales as n^4
    Acc’y:
    ΔHf°±3 , ΔHr±4, ΔHdiss±5, ΔHatom±3, ΔH±4
    D±0.2, IP±0.1
    l±0.007, a±0.9
    v+4.0%

  • B3P86 -
  • Basis:
    B3 hybrid exchange w/ P86 correlation
    Acc’y: v+4.6%


    ab initio Quantum Mechanics



    • Standard (uncorrelated) HF
    Basis:
    Hartree-Fock
    Self Consistent Field
    single Slater determinant/e- configuration
    Pros:
    isodesmic energies
    relative activation enthalpies
    Cons:
    homolysis & atomization enthalpies low
    ΔH†s high w/o correlation
    acrolein isomers
    naphthalene cation symmetry
    O3, F-O-O-F
    radical hyperfine coupling too high x2
    organic bonds short
    M - π bonds long
    favors metal s over d
    wrong N2 orbitals order
    overstablizes hi spin states of metal complexes
    no e- correlation:
    no static correlation: singlet methylene
    no dynamic correlation: dispersion energy (π - π stacking) low
    scales as n^2.7

  • MP2 - 2nd Order Moller Plesset ( = Many Body Perturbation Theory)
  • Basis:
    Rayleigh-Schrodinger perturbation theory
    Taylor Series expansion, truncated at 2nd order
    Pros:
    size consistent
    dynamic correlation for dispersion forces:
    CH4 - CH4 binding
    π - π stacking interaction
    bond breaking
    anomeric effect
    Cons:
    not variational
    transition metals
    overbinds CO2, PO
    free radicals too stable
    O3 frequencies
    bonds long
    greater BSSE
    diverges for e- gas
    diffuse orbitals, extended system
    scales as n^5
    Acc'y:
    ΔHf°±3, ΔHr±4, ΔHdiss±7, ΔHatom-22, ΔH†±11
    l+0.01, a±1
    v+6.0% w/ 6-31G*, +6.7% w/ 6-31G**, +5.3% w/ 6-311G**

  • MP4 - 4th order Moller-Plesset
  • Cons: scales as n^7

    • CCD - Coupled Cluster, doubles
    Basis: double excitations "coupled" to reference configuration
    Pros:
    includes correlation
    complete to order for double excitations

  • CCSD - Coupled Cluster, singles, doubles
  • Basis: single & double excitations "coupled" to reference configuration
    Pros:
    includes correlation
    complete to order for single and double excitations
    includes most quadruple & hextuple excitation effects
    scales as n^6

  • CCSD(T) - Coupled Cluster, singles, doubles with approximate triples
  • Basis:
    single & double excitations "coupled" to reference configuration
    triples contributions perturbatively
    Pros:
    includes correlation
    size consistent
    popular for high level method
    less spin contamination
    transition metals
    O3 frequencies
    Cons:
    overbinds CO2
    not variational
    greater BSSE
    scales as n^5-7

  • CCSDT - Coupled Cluster, singles, doubles, & triples

  • Basis: single, double, & triple excitations "coupled" to reference configuration
    Cons: scales as n^8

    • CI - Configuration Interaction
    Basis:
    HF reference determinant/e- configuration
    expand reference configuration into series of excited configurations
    interaction with excited configurations used as many e- basis set
    Pros:
    dynamic correlation
    more flexible wavefunctions
    Cons: truncated forms not size consistent

    • CIS -
    Basis:
    CI w/ single excitation configurations only
    HF reference determinant
    Pros: electronic spectra
    Cons:
    no e- correlation
    not size consistent
    excited state properties
    potential energy surfaces

  • CID -
  • Basis:
    CI w/ double excitation configurations only
    HF reference determinant
    Cons: not size consistent

    • CISD = SDCI -
    Basis:
    CI w/ single and double excitation configurations
    HF reference determinant
    Pros:
    includes correlation
    single & double excitations
    variational
    Cons:
    not size consistent
    scales as n^6

  • QCISD(T) - Quadratic Configuration Interaction, singles, doubles, approximate triples
  • Basis:
    CI w/ single and double excitation configurations
    HF reference determinant
    terms added to CI to make size consistent
    Pros: size consistent
    Cons: scales as n^7
    Acc'y:
    l+0.01, a±1
    v+5%

  • MRCI - Multi-Reference Configuration Interaction
  • Basis:
    more than 1 reference determinant/e- configuration
    interaction w/ excited configurations used as many e- basis set
    Pros:
    a multireference method
    biradicals
    Cons: scales as n^8

    • MR-CISD -
    Basis:
    more than 1 reference determinant/e- configurations
    CI w/ single & double excited configurations
    Pros: a multireference method
    Cons: not dissociation consistent

    • MCSCF - Multi-Configuration SCF
    Basis:
    more than 1 reference determinant/e- configurations
    both, configuration and orbital, coefficients optimized
    a limited type of CI
    Pros: a multireference method

    • CASSCF - Complete Active Space SCF
    Basis:
    full CI "in active space"
    select # of e- and orbitals
    Pros:
    includes correlation
    a multireference method
    Cons: selection of active space

    • GVB - Generalized Valence Bond
    Basis:
    limited type of MCSCF/a multireference method
    use excitations w/i e- pairs
    Pros: dissociation consistent

    • GVB-PP - GVB, Perfect Pairs
    Basis:
    GVB
    CI restricted to doubles

  • GVB-RCI - GVB Restricted Configuration Interaction
  • Basis:
    GVB
    CI w/ singles and doubles

  • QMC - Quantum Monte Carlo
  • Basis:
    correlated basis functions
    evaluate integrals numerically numerical via Monte Carlo
    Pros:
    includes correlation
    most accurate
    Cons: long calculation




    Quantum Mechanics Basis Sets



    • STO-3G -
    Basis:
    minimal basis set
    Slater type orbitals
    3 Gaussian to fit exponential
    Pros: Pauling point
    Atoms:
    H, He
    Li - Ne
    Na - Ar
    K - Kr
    Rb - Xe
    Acc’y:
    ΔHdiss±3, ΔH±5
    D±0.5
    l±0.09, a±5, d±8

  • STO-3G* -
  • Basis:
    STO-3G
    set of polarizing d-functions (5D) added to heavy atoms
    Atoms:
    Na - Ar
    K - Kr
    Rb - Xe
    Acc’y:

    • 3-21G -
    Basis:
    Pople style (Gaussian Type Orbital) basis set
    Valence Double Zeta:
    3 Gaussians function primitives for each core basis functions
    Split Valence:
    2 Gaussians with linked coefficients for each inner valence e-
    1 "uncontracted" (variable) primitive for each outer valence e-
    Pros: Gaussians reduce 4-body mathematical problem to 2-body problem
    Cons:
    cis vs trans acrolein
    amine N too flat
    M-O short
    adsorption energy high
    Atoms:
    H, He
    Li - Ne
    Na - Ar
    K - Kr
    Rb - Xe
    Acc’y:
    ΔHf°±7, ΔHr±15, ΔHdiss-30, ΔH±4
    D±0.4
    l±0.06, a±3, d±20
    v+10.9%

  • 3-21G* = 3-21G(d) -
  • Basis:
    3-21G
    set of polarizing d-functions (6D) added to atoms past 1st row
    Atoms:
    Na - Ar
    K - Kr
    Rb - Xe
    Acc’y:

    • 3-21+G -
    Atoms:
    Li - Ne
    Na - Ar
    K - Kr
    Rb - Xe

  • 3-21++G* -
  • Atoms:
    H, He
    Li - Ne
    Na - Ar
    K - Kr
    Rb - Xe

  • 4-21G -
  • Atoms:
    H, He
    Li - Ne

  • 4-21G* -
  • Basis:
    4-21G
    set of polarized d-functions (6D) added to heavy atoms

  • 4-21G** -

  • 4-31G -
  • Atoms:
    H - He
    Li - Ne
    P - Cl
    Acc’y: l±0.04

    • 4-31G* -
    Basis:
    4-31G
    set of polarizing d-functions (6D) added to heavy atoms

  • 4-31G** -

  • 6-21G -
  • Atoms:
    H - He
    Li - Ne
    Na - Ar

  • 6-21G* -

  • 6-21G** -

  • 6-31G -
  • Basis:
    Pople style (GTO) basis set
    Valence Double Zeta:
    6 Gaussian function primitives for each core basis function
    Split-valence:
    3 Gaussian primitives (linked coefficients) for each inner valence basis function
    1 "uncontracted" (variable) primitive for each outer
    Pros:
    Gaussians reduce 4-body mathematical problem to 2-body problem
    popular
    Atoms:
    H - He
    Li - Ne
    Na - Ar

  • 6-31+G -
  • Pros:
    negative ions
    Rydberg states
    less BSSE w/ diffuse (3rd) primitive Gaussian
    Cons: convergence difficult w/ diffuse

    • 6-31++G -

    • 6-31G* = 6-31G(d) -
    Basis:
    6-31G
    set of polarizing d-functions (6D) added to heavy atoms
    Pros:
    anomeric effect
    accuracy
    most popular, widely used/validated
    Atoms:
    H, He
    Li - Ne
    Na - Ar
    Acc’y:
    ΔHf°±4, ΔHr±7, ΔHdiss-20, ΔHatom-120, ΔH±7
    D±0.5
    l±0.03, a±1
    v+11.7%

  • 6-31G** = 6-31G(d,p) -
  • Basis:
    6-31G*
    set of polarizing p-functions added to H, too
    Pros: less BSSE w/ diffuse (3rd) primitive Gaussians
    Cons: convergence w/ diffuse (3rd) primitive Gaussians
    Acc’y: v+11.2%

    • 6-31+G* = 6-31+G(d) - Augmented 6-31G*
    Basis:
    6-31G*
    set of diffuse s- and diffuse p-functions added to heavy atoms

  • 6-31++G* = 6-31++G(d) - Augmented 6-31+G*
  • Basis:
    6-31+G*
    set of diffuse s-functions added to H, too

  • 6-31+G** = 6-31+G(d,p)-

  • 6-31++G** = 6-31++G(d,p)-

  • 6-311G -
  • Basis:
    Pople style (GTO) basis set
    Valence Triple Zeta:
    6 Gaussian primitives for each core basis functions
    Triple split valence:
    3 primitives (linked coefficients) for each inner valence basis function
    1 uncontracted primitive for 2nd layer of valence
    1 uncontracted primitive for outer layer of valence
    Cons: less flexible than real triple-zeta
    Acc’y: v+10.5%

    • 6-311G* = 6-311G(d) -
    Basis:
    6-311G
    set of polarizing d-functions (5D) added to heavy atoms
    Atoms:
    H - He
    Li - Ne
    Na - Ar

  • 6-311G** = 6-311G(d,p) -
  • Basis:
    6-311G*
    set of polarizing p-functions added to H, too
    Acc’y: v+10.5%

    • 6-311+G** -

    • 6-311+G(3df,2p) -
    Basis:
    6-311G
    diffuse s- and p-functions added to heavy atoms
    3 d- and 1 polarizing f-function added to heavy atoms
    2 polarizing p-functions added to H

    • cc-pVDZ - Correlation Consistent, polarized Valence Double Zeta
    Basis:
    correlation consistent basis set
    Valence Double Zeta
    set of polarizing d-functions (5D) added to heavy atoms
    Pros:
    use with correlated methods
    series converges exponentially to complete basis set limit
    Atoms:
    H-Ne
    B-Ne
    Al-Ar

  • cc-pVDZ+ - Augmented cc-pVDZ
  • Basis: add diffuse functions
    Atoms:
    H
    C-F
    Si-Cl

  • cc-pVDZ++ -

    • cc-pVTZ - Correlation Consistent Valence, polarized Triple Zeta
    Basis:
    correlation consistent basis set
    Valence Triple Zeta
    set of polarizing d-functions (5D) and f-functions added to heavy atoms
    Pros: CH4 - CH4 binding
    Atoms:
    H-He
    B-Ne
    Al-Ar

  • cc-pVTZ+ -
  • Basis: add diffuse functions
    Atoms:
    H
    C-F
    Si-Cl

  • cc-pVTZ++ -

  • cc-pVQZ - Correlation Consistent, polarized Valence Quadruple Zeta
  • Basis:
    correlation consistent basis set
    Valence Quadruple Zeta

  • cc-pV5Z - Correlation Consistent, polarized Valence Quintuple Zeta
  • Basis:
    correlation consistent basis set
    Valence Quintuple Zeta

  • MIN -
  • Basis:
    minimal basis set
    numeric
    Pros: DFT
    Atoms: not limited to set

    • DN - Double Numeric
    Basis:
    Double Zeta
    numeric basis set
    exact numerical function from spherical atom

  • DND -
  • Basis:
    Double Zeta
    numeric basis set
    set of polarizing functions (p- and d-) on heavy atoms
    Pros: more accurate than 6-31G*
    Atoms: not limited

    • DNP - Double Numeric with Polarization
    Basis:
    Double Zeta
    numeric basis set
    set of polarizing functions (s-, p-, d-) on all atoms
    Pros:
    DFT
    more accurate than 6-31G**
    speed
    Cons: sensitive to orientation
    Atoms: not limited

    • DZ94 - Double Zeta
    Basis:
    Double Zeta
    contracted Gaussians, optimized for (local) DFT
    Atoms:
    H - He
    Li - Ne
    Na - Ar
    K - Kr
    Rb - Xe

  • DZ94P - Double Zeta with Polarization
  • Basis:
    DZ94
    polarization functions (1 angular momentum # higher than valence) added
    Atoms:
    H - He
    Li - Ne
    Na - Ar
    K - Kr
    Rb - Xe

  • DZV - Double Zeta Valence
  • Basis:
    Dunning/Hay & Binning/Curtiss
    Valence Double Zeta
    Atoms:
    H - He
    Li - Ne
    Al - Ar
    Ga - Kr

  • DZVP - Double Zeta Valence with Polarization
  • Basis:
    Valence Double Zeta
    contracted Gaussians, optimized for (local) DFT
    (~ 6-41G* ?)
    polarization d-functions added to heavy atoms
    Atoms:
    H - He
    Li - Ne
    Na - Ar
    K - Kr
    Rb - Xe

  • DZVP2 -
  • Basis:
    DZVP
    polarization functions added to H, too
    Atoms:
    H - He
    Li - Ne
    Al -Ar
    Sc - Zn

  • D95 -
  • Atoms:
    H
    Li - Ne
    Al - Cl

  • D95* -
  • Basis:
    D95
    set of polarizing functions (6D) added to heavies

  • D95V -
  • Atoms:
    H
    Li - Ne

  • D95V* -
  • Basis:
    D95V
    set of polarizing functions (6D) added to heavies

  • TZ94 - Triple Zeta
  • Basis:
    Triple Zeta
    contracted Gaussians, optimized for (local) DFT
    Atoms:
    H - He
    Li - Ne
    Na - Ar
    K - Kr
    Rb - Xe

  • TZ94P - Triple Zeta with Polarization
  • Atoms:
    H - He
    Li - Ne
    Na - Ar
    K - Kr
    Rb - Xe

  • TZV -
  • Basis:
    Triple Zeta Valence
    6-311G & McLean/Chandler
    Gaussian primitives
    Atoms:
    Li - Ne
    Na - Ar
    K - Zn

  • TZVP - Triple Zeta Valence with Polarization
  • Basis:
    Triple Zeta Valence
    (~ 6-311G* ?)
    optimized for (local) DFT
    Atoms:
    H - He
    B - Ne
    Al - Ar

  • LAV1S ( = LANL1MB ?) -
  • Basis:
    Los Alamos (Hay-Wadt) Effective Core Potentials
    Minimal basis set: Valence only
    STO-3G for non ECP atoms
    Atoms:
    Na - Ar
    K - Kr
    Rb - Xe
    Cs - La, Hf - Bi

  • LAV2D (= LANL1DZ ? LANL2DZ ?) -
  • Basis:
    Los Alamos (Hay-Wadt) ECP's
    Double Zeta: Valence only
    D95V basis for non ECP's
    Atoms:
    Na - Ar
    K - Kr
    Rb - Xe
    Cs - La, Hf - Bi

  • LAV2P -
  • Basis:
    Los Alamos Effective Core Potentials
    Double Zeta: Valence only
    6-31G basis for non ECP's
    Atoms:
    Na - Ar
    K - Kr
    Rb - Xe
    Cs - La, Hf - Bi

  • LAV3D -
  • Basis:
    Los Alamos Effective Core Potentials
    Triple Zeta: Valence only
    D95 basis for non ECP's
    Atoms:
    Na - Ar
    K - Kr
    Rb - Xe
    Cs - La, Hf - Bi

  • LAV3P -
  • Basis:
    Los Alamos Effective Core Potentials
    Triple Zeta: Valence only
    pseudospectral
    6-31G for non ECP's
    Atoms:
    Na - Ar
    K - Kr
    Rb - Xe
    Cs - La, Hf - Bi

  • LACVD -
  • Basis:
    Los Alamos Effective Core Potentials
    Double Zeta: Valence and outermost core
    D95 basis for non ECP's
    Atoms:
    K - Cu
    Rb - Ag
    Cs - La, Hf - Au

  • LACVP -
  • Basis:
    Los Alamos Effective Core Potentials
    Double Zeta: Valence and outermost core
    6-31G basis for non ECP's
    pseudospectral
    Pros:
    correlated wavefunctions
    charge transfer effects
    3rd row & higher elements
    d(0) metals
    Atoms:
    K - Cu
    Rb - Ag
    Cs - La, Hf - Au

  • LACV3P -
  • Basis:
    Los Alamos Effective Core Potentials
    Triple Zeta: Valence & outermost core
    6-311G for non ECP's
    pseudospectral
    Pros:
    atomic state splittings
    correlated wavefunctions
    3rd row & higher elements
    d(0) metals
    charge transfer
    Atoms:
    K - Cu
    Rb - Ag
    Cs - La, Hf - Au

  • LACV3P++ -
  • Basis:
    LACV3P
    diffuse added to all atoms, including H & He
    Pros:
    low spin M(0), late 1st row transition metal complexes
    anions

  • CEP = SBK - Stevens-Bash-Krauss-Jasien-Cundari
  • Basis:
    Effective Core Potentials
    Double Zeta: valence only
    -31G splits
    Atoms:
    Li - Ne
    Na - Ar
    K - Kr
    Rb - Xe
    Cs - Rn

  • CEP-4 -

  • CEP-31 -

  • CEP-121 -

  • HW - Hay - Wadt ECP's
  • Basis:
    Double Zeta: valence only
    -21 splits
    Atoms:
    Na - Ar
    K - Kr
    Rb - Xe

  • MSV -
  • Atoms:
    H - He
    Li - Ne
    Na - Ar
    K - Ru, Pd - Xe

  • MSV* -
  • Basis:
    MSV
    set of polarizing d-functions (5D) added


    Salt Crystal

    (Grain of Salt)

    The information above has been collected from various published results, documentation, and personal experience. This list is updated as information comes to my attention and as time allows, but as rapidly as methods evolve, some info is no doubt out of date and/or incomplete. (Accuracies are averages of typical literature comparisons, for instance, which, of course, is dependent on the systems included in the published study.) Consequently, this compilation is meant more as an aid to help remember the strengths and limitations of each method, rather than as a complete and authoritative reference.


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    6/11/00 Ernie Chamot / Chamot Labs / (630) 637-1559 / echamot@chamotlabs.com
    Modified: Thu Nov 30 06:51:34 2000 GMT
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