Input keywords¶
This manual documents the input for the MOPAC engine used together with the AMS driver. If you are not yet familiar with the AMS driver setup, we highly recommend reading the introductory section in the AMS manual.
The MOPAC engine is selected and configured in the AMS input with
Engine MOPAC
... keywords documented in this manual ...
EndEngine
This page documents all keywords of the MOPAC engine input, basically the
contents of the Engine MOPAC block in the AMS input file.
General remarks on the input syntax can be found in the AMS manual.
See also
The Examples section of this manual contains several example calculations
Model Hamiltonian¶
The most important keyword in the MOPAC engine input is the model selection:
Model- Type
Multiple Choice
- Default value
PM7
- Options
[AM1, MNDO, MNDOD, PM3, RM1, PM6, PM6-D3, PM6-DH+, PM6-DH2, PM6-DH2X, PM6-D3H4X, PM7]
- GUI name
Method
- Description
Selects the model Hamiltonian to use in the calculation. AM1: Use the AM1 Hamiltonian. MNDO: Use the MNDO Hamiltonian. MNDOD: Use the MNDO-d Hamiltonian. RM1: Use the RM1 Hamiltonian. PM3: Use the MNDO-PM3 Hamiltonian. PM6: Use the PM6 Hamiltonian. PM6-D3: Use the PM6 Hamiltonian with Grimme’s D3 corrections for dispersion. PM6-DH+: Use the PM6 Hamiltonian with corrections for dispersion and hydrogen-bonding. PM6-DH2: Use the PM6 Hamiltonian with corrections for dispersion and hydrogen-bonding. PM6-DH2X: Use PM6 with corrections for dispersion and hydrogen and halogen bonding. PM6-D3H4: Use PM6 with Rezac and Hobza’s D3H4 correction. PM6-D3H4X: Use PM6 with Brahmkshatriya, et al.’s D3H4X correction. PM7: Use the PM7 Hamiltonian. PM7-TS: Use the PM7-TS Hamiltonian (only for barrier heights)
The default PM7 model [2] is the latest parametrization for MOPAC and should be the most accurate for most calculations.
Sparkles- Type
Bool
- Default value
No
- Description
Represent lanthanides by their fully ionized 3+ sparkles. That is, they have no basis set, and therefore cannot have a charge different from +3. When using sparkles, the geometries of the lanthanides are reproduced with good accuracy, but the heats of formation and electronic properties are not accurate.
UnpairedElectrons- Type
Integer
- GUI name
Spin polarization
- Description
If this key is present, a spin-unrestricted calculation with the specified number of unpaired electrons is performed. If this key is not present the number of unpaired electrons is determined automatically (0 for systems with an even number of electrons, 1 for radicals), and a restricted or unrestricted calculation is performed accordingly.
Solvation¶
Solvation effects can be included via the COSMO model.
Solvation
Enabled Yes/No
NSPA [...]
Solvent
Eps float
Name [...]
Rad float
End
End
Solvation- Type
Block
- Description
Options for the COSMO (Conductor like Screening Model) solvation model.
Enabled- Type
Bool
- Default value
No
- GUI name
Use COSMO
- Description
Use the Conductor like Screening Model (COSMO) to include solvent effects.
NSPA- Type
Multiple Choice
- Default value
42
- Options
[12, 32, 42, 92, 122, 162, 252, 272, 362, 482, 492, 642, 752]
- GUI name
NSPA
- Description
Maximum number of COSMO surface points per atom.
Solvent- Type
Block
- Description
Solvent details
Eps- Type
Float
- GUI name
Dielectric constant
- Description
User-defined dielectric constant of the solvent (overrides the Eps value of the solvent defined in ‘Name’)
Name- Type
Multiple Choice
- Default value
Water
- Options
[CRS, AceticAcid, Acetone, Acetonitrile, Ammonia, Aniline, Benzene, BenzylAlcohol, Bromoform, Butanol, isoButanol, tertButanol, CarbonDisulfide, CarbonTetrachloride, Chloroform, Cyclohexane, Cyclohexanone, Dichlorobenzene, DiethylEther, Dioxane, DMFA, DMSO, Ethanol, EthylAcetate, Dichloroethane, EthyleneGlycol, Formamide, FormicAcid, Glycerol, HexamethylPhosphoramide, Hexane, Hydrazine, Methanol, MethylEthylKetone, Dichloromethane, Methylformamide, Methypyrrolidinone, Nitrobenzene, Nitrogen, Nitromethane, PhosphorylChloride, IsoPropanol, Pyridine, Sulfolane, Tetrahydrofuran, Toluene, Triethylamine, TrifluoroaceticAcid, Water]
- GUI name
Solvent
- Description
Name of a pre-defined solvent. A solvent is characterized by the dielectric constant (Eps) and the solvent radius (Rad).
Rad- Type
Float
- Unit
Angstrom
- GUI name
Radius
- Description
User-defined radius of the solvent molecule (overrides the Rad value of the solvent defined in ‘Name’).
Properties¶
Properties
StaticPolarizability Yes/No
pKa Yes/No
End
Properties- Type
Block
- Description
MOPAC can calculate various properties of the simulated system. This block configures which properties will be calculated.
StaticPolarizability- Type
Bool
- Default value
No
- Description
Calculate the static polarizability. An electric field gradient is applied to the system, and the response is calculated. The dipole and polarizability are calculated two different ways, from the change in heat of formation and from the change in dipole. A measure of the imprecision of the calculation can be obtained by comparing the two quantities.
pKa- Type
Bool
- Default value
No
- GUI name
pKa
- Description
If requested, the pKa of hydrogen atoms attached to oxygen atoms is calculated and printed.
The calculation of Natural Bond Orbitals can be requested with the following keyword:
CalcLocalOrbitals Yes/No
CalcLocalOrbitals- Type
Bool
- Default value
No
- Description
Compute and print the localized orbitals, also known as Natural Bond Orbitals (NBO). This is equivalent to the LOCAL mopac keyword.
The calculation of bond orders can be requested in the AMS Properties block.
Technical settings¶
SCF
CampKingConverger Yes/No
ConvergenceThreshold float
MaxIterations integer
End
SCF- Type
Block
- Description
Options for the self-consistent field procedure.
CampKingConverger- Type
Bool
- Default value
No
- GUI name
Use Camp-King
- Description
Use the Camp-King SCF converger. This is a very powerful, but CPU intensive, SCF converger.
ConvergenceThreshold- Type
Float
- Default value
0.0001
- Unit
kcal/mol
- Description
If the difference in energy between two successive SCF iterations is smaller than this value, the SCF procedure is considered converged.
MaxIterations- Type
Integer
- Default value
2000
- Description
Maximum number of SCF iterations.
With the MOZYME method the standard SCF procedure is replaced with a localized molecular orbital (LMO) method. This can speed-up the calculation of large molecules. Although a job that uses the MOZYME technique should give results that are the same as conventional SCF calculations, in practice there are differences. Most of these differences are small, but in some jobs the differences between MOZYME and conventional SCF calculations can be significant. Use with care.
Mozyme- Type
Bool
- Default value
No
- Description
Replace the standard SCF procedure with a localized molecular orbital (LMO) method. The time required for an SCF cycle when Mozyme is used scales linearly with system size.
Extra keywords¶
Finally it is possible to pass any other keywords directly to the MOPAC program [1]. The full list of keywords can be found on the standalone MOPAC manual.
Keywords string
Keywords- Type
String
- Description
A string containing all the desired custom MOPAC keywords. Basically for anything not directly supported through AMS.
These keywords are just literally passed through to MOPAC program which the AMS MOPAC engine wraps, without any checking in AMS. One should therefore be very careful with this, as it is very easy to set up completely non-sensical calculations in this way.
Note: The following keywords have been either removed or renamed in our version of MOPAC and they should not be used in the Keywords key: 0SCF, 1SCF, A0, ADD, AIDER, AIGIN, AIGOUT, ALT_A, ALT_R, ANGSTROMS, AUTOSYM, BANANA, BAR, BCC, BFGS, BIGCYCLES, BIRADICAL, CHAINS, COMPARE, CVB, DDMAX, DDMIN, DFORCE, DFP, DMAX, DRC, ECHO, EF, FLEPO, FORCE, FREQCY, GNORM, H, HTML, INT, IONIZE, IRC, ISOTOPE, KINETIC, LBFGS, LET, LOCATE, MODE, NOCOMMENTS, NOOPT, NORESEQ, NOSWAP, NOTER, NOTHIEL, NOTXT, OPT, P, PDB, PDBOUT, POINT, POINT1, POINT2, RABBIT, RECALC, RMAX, RMIN, SIGMA, SLOG, SMOOTH, SNAP, START_RES, STEP, STEP1, STEP2, SYBYL, T, THERMO, THREADS, TIMES, TRANS, TS, VELOCITY, X, XENO, XYZ,, AM1, LOCAL, BONDS, CHARGE, UHF, CAMP, KING, ITRY, EPS, FIELD, pKa, STATIC, CYCLES, PRESSURE, SPARKLE.