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N.B.! These descriptors can be only used for model development on OCHEM web site and cannot be exported.

Most of Chemaxon descriptors (also known as: Chemaxon calculators) are implemented in OCHEM platform and can be calculated for any set of molecules. Desscriptors implemented are those which return munerical or boolean results. Unimplemented descriptors are those which return results not suitable for modeling purposes such as molecules, formula, or fingerprints. Also calculators that require specific input parameters are not implemented. Example of these calculators are those that check whether certain atom is assymetric, whether 2 atoms are connected, or calculate the angle between 3 specified atoms.

The implemented descriptors are divided into 7 groups: Elemental Analysis, Charge, Geometry, Partitioning, Protonation, Isomers, and Others

Descriptor NameDescriptor classDefinitionConsiders pH during calculation
atomcountElemental AnalysisNumber of atoms in the moleculeno
exactmassElemental AnalysisExact molecule mass calculation based on the most frequent natural isotopes of the elementsno
massElemental AnalysisMolecule mass calculationno
   no
averagemolecularpolarizabilityChargeAverage molecular polarizability calculationyes
formalchargeChargeFormal charge calculationyes
molecularpolarizabilityChargeMolecular polarizability calculationyes
   no
aliphaticatomcountGeometryAliphatic atom countno
aliphaticbondcountGeometryAliphatic bond countno
aliphaticringcountGeometryAliphatic ring countno
aliphaticringcountofsizeGeometryAliphatic ring count of sizeno
aromaticatomcountGeometryAromatic atom countno
aromaticbondcountGeometryAromatic bond countno
aromaticringcountGeometryAromatic ring countno
aromaticringcountofsizeGeometryAromatic ring count of sizeno
asymmetricatomcountGeometryThe number of asymmetric atomsno
balabanindexGeometryThe Balaban indexno
bondcountGeometryBond countno
carboaliphaticringcountGeometryCarboaliphatic ring countno
carboaromaticringcountGeometryCarboaromatic ring countno
carboringcountGeometryCarbo ring countno
chainatomcountGeometryChain atom countno
chainbondcountGeometryChain bond countno
chiralcentercountGeometryThe number of tetrahedral stereogenic center atomsno
dreidingenergyGeometryCalculates the dreiding energy of a conformer of the molecule in kcal/molno
fragmentcountGeometryFragment countno
fusedaliphaticringcountGeometryThe number of fused aliphatic rings (SSSR smallest set of smallest aliphatic rings)no
fusedaromaticringcountGeometryThe number of fused aromatic rings (SSSR smallest set of smallest aromatic rings)no
fusedringcountGeometryThe number of fused rings (SSSR smallest set of smallest rings)no
hararyindexGeometryHarary indexno
heteroaliphaticringcountGeometryHeteroaliphatic ring countno
heteroaromaticringcountGeometryHeteroaromatic ring countno
heteroringcountGeometryHetero ring countno
hyperwienerindexGeometryHyper Wiener indexno
largestringsizeGeometryLargest ring sizeno
largestringsystemsizeGeometryLargest ring system sizeno
maximalprojectionareaGeometryCalculates the maximal projection areano
maximalprojectionradiusGeometryCalculates the maximal projection radiusno
maximalprojectionsizeGeometry no
minimalprojectionareaGeometryCalculates the minimal projection areano
minimalprojectionradiusGeometryCalculates the minimal projection radiusno
minimalprojectionsizeGeometry no
molecularsurfaceareaGeometryMolecular Surface Area calculation (3D)yes
plattindexGeometryThe Platt indexno
randicindexGeometryThe Randic indexno
polarsurfaceareaGeometryTopological Polar Surface Area calculation (2D)yes
ringatomcountGeometryRing atom countno
ringbondcountGeometryRing bond countno
ringcountGeometryRing countno
ringcountofsizeGeometryRing count of sizeno
ringsystemcountGeometryThe number of ring systemsno
ringsystemcountofsizeGeometryRing system count of sizeno
rotatablebondcountGeometryRotatable bond countno
smallestringsizeGeometrySize of smallest ringno
smallestringsystemsizeGeometrySmallest ring system sizeno
stereodoublebondcountGeometryThe number of stereo double bondsno
szegedindexGeometrySzeged indexno
volumeGeometryCalculate the van der Waals volume of the moleculeno
wienerindexGeometryWiener indexno
wienerpolarityGeometryWiener polarityno
vdwsaGeometryVan der Waals Surface Area calculationyes
   no
logpPartitioninglogP calculation: logP of uncharged species, or, in the case of zwitterions, logD at pIno
logdPartitioninglogD calculationyes
   no
isoelectricpointprotonationDescriptorsIsoelectric point calculationno
   no
doublebondstereoisomercountIsomersThe number of double-bond stereoisomers of the moleculeno
stereoisomercountIsomersThe number of stereoisomers of the moleculeno
tautomercountIsomersThe number of tautomersno
tetrahedralstereoisomercountIsomersThe number of tetrahedral stereoisomers of the moleculeno
   no
acceptorcountOthersHydrogen bond acceptor atom count in moleculeyes
acceptorsitecountOthersHydrogen bond acceptor multiplicity in moleculeno
donorcountOthersHydrogen bond donor atom count in moleculeyes
donorsitecountOthersHydrogen bond donor multiplicity in moleculeyes
hmopienergyOthersHMO Pi energyyes
pienergy *OthersPi energyyes
msaccOthersHydrogen bond acceptor average multiplicity over microspecies by pHno
msdonOthersHydrogen bond donor average multiplicity over microspecies by pHno
resonantcountOthersThe number of resonant structuresno
  • - Descriptors that will not be supported in in future versions.

pH descriptors

Calculation of some descriptors require consideration of pH value. User is allowed 3 options for pH:

  • All: This calculates the value of the descriptor over the pH range from 0 to 14 taking 1 pH unit increments at a time. Additionally, the descriptor value at pH 7.4 is calculated.
  • Specific value: calculates the value of the descriptor at the speicifed pH.
  • Specific range: calculates the value of the descriptor over the pH range specified between "from" until "to" taking pH unit increments equal to the value specifid in "step". Additionally, the descriptor value at pH 7.4 is calculated.

Descriptors which consider pH value during their calculation are: veragemolecularpolarizability, formalcharge, molecularpolarizability, molecularsurfacearea, polarsurfacearea, vdwsa, logd, acceptorcount, acceptorsitecount, donorcount, donorsitecount, hmopienergy, pienergy

Ring size

The following descriptors measure the ring size: aliphaticringcountofsize, aromaticringcountofsize, ringcountofsize, ringsystemcountofsize They are calculated for 3-, 4-, 5-, 6-, 7-, and 8-membered rings.

The following calculators are unable to handle molecules with multiple fragments, instead OCHEM platform replaces it with a "missing descriptor value". Currently this value is set to 0. We plan to allow the user to specify such value in the future or even skip the whole molecule altogether from the dataset.

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