Required Cards:

SPECIES_NAME <string>

Name of immobile species to undergo first-order decay.

RATE_CONSTANT or HALF_LIFE (but not both)

Optional Cards:

RATE_CONSTANT <float>

First-order rate constant [1/sec]

HALF_LIFE <float>

half life of species [sec].

Note that rate constant or half life units other than sec or 1/sec may be specified.

Examples:

CHEMISTRY
  PRIMARY_SPECIES
    ...
  /
  IMMOBILE_SPECIES
    D(im)
  /
  ...
  IMMOBILE_DECAY_REACTION
    SPECIES_NAME D(im)
    RATE_CONSTANT 1.d-9
  /
  ...
/