Dear Reza,
These reactions are also included in CMAQ and are temperature dependent. You can calculate rate constants at different temperatures. Rate constants for most of these reactions use fall-off type expression.
For example, you can look at mech_cb6r5_ae7_aq and find the following reaction:
HO2 + HO2 = H2O2 %3 # 2.20E-13@-600 & 1.90E-33@-980;
In RXNS_FUNC_MODULE.F90 file, you will find:
! Reaction Label R19
RKI( NCELL, 19) = CFACT * FALLOFF_T09( INV_TEMP, CAIR, &
& 2.2000D-13, 6.0000D+02, 1.9000D-33, &
& 9.8000D+02 )
ARRHENUIS_T09 is defined as follows:
REAL( 8 ) FUNCTION FALLOFF_T09(INV_TEMP,CAIR,A1,C1,A2,C2)
! rate constant for CMAQ fall off reaction type 9
IMPLICIT NONE
REAL( 8 ), INTENT( IN ) :: INV_TEMP
REAL( 8 ), INTENT( IN ) :: CAIR
REAL( 8 ), INTENT( IN ) :: A1
REAL( 8 ), INTENT( IN ) :: C1
REAL( 8 ), INTENT( IN ) :: A2
REAL( 8 ), INTENT( IN ) :: C2
! Local:
REAL( 8 ) K1
REAL( 8 ) K2
INTRINSIC DEXP
K1 = A1 * DEXP( C1 * INV_TEMP )
K2 = A2 * DEXP( C2 * INV_TEMP )
FALLOFF_T09 = K1 + K2 * CAIR
RETURN
END FUNCTION FALLOFF_T09
INV_TEMP is the reciprocal of air temperature. CAIR (M) is the air number density [molecule/cm^3] and can be calculated using pressure and temperature. Similarly, you can find other reactions in mech_cb6r5_ae7_aq and corresponding rate constants in RXNS_FUNC_MODULE.F90. Please let me know if you need any other help.
Thanks,
Sarwar