The species involved in the CollisionDB processes are identified using the conventions of the pyvalem library:

• Atoms are identified by their element symbols:
  • H
  • Li, etc.
• Molecules are sequences of element symbols, possibly with their numerical stoichiometries given (no underscore characters, _):
  • BeH
  • H2O
  • CH3CH2OH
• Any charges are specfied after the formula in the format +, -, +q, -q (no caret characters, ^):
  • H+
  • Be+4
  • CO3-2
• Isotopes are specified in parentheses, with the mass number preceding the element symbol (no caret characters, ^); deuterium and tritium may be specified as D and T, respectively:
  • (6Li)
  • (13C)

Quantum states are specified in any order using the following conventions:

• Atomic configurations as orbitals separated by a period, .:
  • 1s
  • 1s2
  • 1s2.2s
  • 1s2.2s2.2p4
• Atomic term symbols as follows (2S+1)L_J: spin multiplicity, 2S+1, followed by orbital angular momentum quantum number label and, optionally, J quantum number; odd parity is optionally specified with the character (o):
  • 2P
  • 2Po_1/2
  • 4D
  • 1S_0
• Individual quantum numbers as key-value pairs (no spaces around the = sign):
  • n=1
  • |m|=1
• Linear molecule electron configurations:
  • 1σ
  • 1σ2
  • 1σg2
  • 1sigmau2.2sigmag1
  • 1sigmag
  • 1σg2.1σu2.2σg2.2σu2.1πu4.3σg2
• Molecular term symbols (with or without state labels):
  • 1Σ+g
  • 1SIGMA+g
  • a(3SIGMA-g)
  • X(3Π)
  • X(3PI)
  • A(1A")