This document describes the format of the chemkin-II input files.

Chemkin Interpreter input

For the complete description of the Chemkin Interpreter input file, see the following document.

'Chemkin-II: A Fortran Chemical Kinetics Package for the Analysis of Gas-Phase Chemical Kinetics,' R. J. Kee, F. M. Rupley, and J. A. Miller, Sandia Report, SAND89-8009B (1995).

Input-file structure

Below is an example input.

!-----------------------------------------------------------------------
!                     'exmHCO01.inp'
!   C-H-O system machanism based on ...
!-----------------------------------------------------------------------
ELEMENTS
  H C N O
END
!-----------------------------------------------------------------------
SPECIES
  H2 H O2 O OH HO2 H2O2 H2O N2
  CH3 CH4
...(snip)...
END
!-----------------------------------------------------------------------
THERMO
CH3               121286C   1H   3          G  0300.00   5000.00  1000.00      1
 0.02844051E+02 0.06137974E-01-0.02230345E-04 0.03785161E-08-0.02452159E-12    2
 0.16437809E+05 0.05452697E+02 0.02430442E+02 0.11124099E-01-0.01680220E-03    3
 0.16218288E-07-0.05864952E-10 0.16423781E+05 0.06789794E+02                   4
END
!-----------------------------------------------------------------------
REACTIONS  KJOULES/MOLE  MOLECULES
  H + CH3 (+M) = CH4 (+M)        3.50E-10   0.      0.    !94CEC (300-1000K)
     LOW /1.726E-24 -1.8 0./                              ! for M=Ar
     TROE /0.63 61. 3315./
...(snip)...
END
!-----------------------------------------------------------------------

The input should be in the following order. The thermo block may be skipped.
- Elements block
  'ELEMENTS' ~ 'END'
- Species block
  'SPECIES' ~ 'END'
- Thermo block
  'THERMO' ~ 'END'
- Reactions block
  'REACTIONS' ~ 'END'
At any position in the format-free part, an exclamation mark, '!', can be inserted. From the exclamation mark to the end of the line is skipped by the parser as a comment. Not allowed in the thermo block which is a fixed-format part.

Elements block

List all the elements contained in the species (that is, atoms and molecules) to be considered. Place the symbols of elements delimited by a space (may be multiple spaces) or a line-feed between 'ELEMENTS' and 'END'. For element symbols, either of upper, lower, or mixed case (e.g. 'AR' 'ar' or 'Ar') is allowed but it must be case-sensitively identical with that used in the thermodata.

example-1

 ELEMENTS H O AR CL END

example-2

 ELEMENTS
  H O C N HE
 END

Species block

List all the species (atoms and molecules) to be considered. Similarly to the elements, place the names of the species delimited by spaces or a line-feed between 'SPECIES' and 'END'.
The species name cannot exceed 16 charactors, and the first letter should not be numeric, '+', nor '='. It does not need to be a chemcal formula such as CH4' or 'C2H6', but should be identical with the name in the therm.dat or thermo block. (For example, formyl radical in the default therm.dat is named as 'HCO', not 'CHO')
When the chemical formula is not enough to identify the species, refer to The Chemkin Thermodynamic Data Base (SAND87-8215B). For example, there are three species with C3H4 chemcal formula in therm.dat. They are named as 'C3H4', 'C3H4C', and 'C3H4P' corresponding to allene, cyclopropene, and propyne, respectively.

Thermo block

This block is an option. When the all species in the Species Block are registered in the therm.dat, and if you choose to use them, this block can be skipped.
Place the coefficients for thermodynamic functions in four-lines fixed-format per one species between 'THERMO' and 'END'. The format is identical with that of therm.dat and refer to the Thermodata file (therm.dat) section for details.
With Chemkin, thermodynamic data should be given for all the species considered. Since thermodynamic functions are required to calculate the rate constants for reverse reactions (See Reactions block) and the heat balance. In an exceptional case, when no reverse reaction should be considered and the temperature change can be negligible (which may no be rare as the condition of the laboratory kinetic experiments ...), thermodynamic data is not necessary. However, even for the isothermic calculation without any reversible reaction, Chemkin requests the thermodata. In such a case, one may register dummy (may be totally inaccurate) thermodata to avoid the error of Chemikin. For this case, do not modify the therm.dat with dummy data, but register it in here in the Thermo block.

Reactions block

List reaction equations with rate parameters for the reactions to be considered in this block. The 'REACTIONS' or 'END' statement should appear as an independent line, and one reaction should be described in a line. A reaction should be described in the order of the reaction equation and rate parameters.

Reaction equation

A reaction equation can be given as the following format.
```
reac1 + reac2 + reac3 = prod1 + prod1 + prod3
```
The number of the reactants or the products must be no less than one and no more than three. The name of the reactant or product must be identical with the one declared in the Species Block except for the following exceptions.
- exception-1
  A reaction with two or more identical reactants or products may be written as the following example.
```
2OH = H2O2
```
- exception-2
  M is a special third-body reactant (and product) representing the all the species. It may be used as the following example.
```
H + H + M = H2 + M
```
  Details of the reactions with third-body will be given below.
One of the following separators can be used between the reactants and products.
```
=>
```
Indicates an irreversible reaction, that is, only the forward reaction is considered.
```
= or <=>
```
Indicates an reversible reaction. The rate constant for the reverse reaction is calculated from the thermodynamic data unless it is specified by using REV keyword.

Rate constants and unit

Rate constants are calculated by the modified Arrhenius equation,
(1)
The parameters, A, b, and E_a should be specified in this order separated by space charactors. In the top line of the Reactions Block, two keywords specifying units for the activation energy and preexponential factor may placed after 'REACTIONS' delimited with space charactors. The default is cal/mol for the activation energy and mol-cm-s-K for the preexponential factor. The acceptable keywords are as follows.
- CAL/MOLE, KCAL/MOLE, JOULES/MOLE, KJOULES/MOLE, KELVINS
- MOLES, MOLECULES
The unit for the preexponential factor may be either mol-cm-s-K (default, MOLES) or molecules-cm-s-K (MOLECULES). No choice for the unit such as mol/l (= mol dm⁻³).

Reactions involving third-body

Depending on how the rate constants changes with the pressure, on of the following three forms is used. In scientific papers, the reaction involving the third-body always written with the apparent 'M' irrespective of the pressure dependence of the rate constant. The Chemkin input form is a convenience to clarify the way to calculate the pressure dependence of the rate constants and do not confuse.
- form-1
```
A + B = C
A + B => C
```
  Rate constant is considered to be independent of pressure.
- form-2
```
A + B + M = C + M
A + B + M => C + M
```
  Rate constant is assumed to be in low-pressure limiting region.
- form-3
```
A + B (+ M) = C (+ M)
A + B (+ M) => C (+ M)
```
  Rate constant is in the fall-off region. Auxiliary input is required to specify the formula for the pressure dependence.
Auxiliary input for the pressure dependence is required when the form-3 above is specified. The following auxiliary inputs are accepted.
- Lindemann formula
  Evaluate the pressure dependence by using the Lindemann formula,
  (2)
  where X is a reduce pressure normalized by the fall-off pressure [M]_c.
  (3), (4)
  Write A, b, and E_a for the high-pressure limit in the reaction equation line. The rate parameters for the low-pressure limit should be given in the next line by using LOW keyword as follows.
```
A + B (+ M) = C (+ M)   2.3E14  0.0   156.2
                   LOW/ 6.3E27 -2.6   -54.3 /
```
- Troe's formula
  Evaluate the pressure dependence by using the Troe's formula,
  (5)
  (6)
  (7)
  (8)
  (9)
  (10)
  Similarly to the case of Lindemann formula, give the rate parameters for high-pressure and low-pressure limits in the first and second lines, and in the third line, give the parameters a, T***, T*, and T**, in this order by using TROE keyword. The last parameter, T**, is optional and the last term of eq. (10) will be omitted when this parameter is omitted. Below is an example.
```
A + B (+ M) = C (+ M)   2.3E14  0.0 156.2
                   LOW/ 6.3E27 -2.6 -54.3 /
                  TROE/ 0.604 6980. 132. /
```
  In general, the rate parameters for the low-pressure limit or the low-pressure part of the fall-off region depends largely on the buffer gas. This effect can be specified as an enhancement factor. Here is an example.
```
A + B + M = C + M     6.3E27  -2.6  -54.3
       CO/1.9/ H2/1.7/ CO2/3./ H2O/5./
```
  In this example, the low-pressure limiting rate constant is multiplied by 1.9, 1.7, 3., and 5. for CO, H2, CO2, and H2O, respectively. Similar input can be added for the fall-off reactions.
The form-1 input may be followed by a sequence of PLOG keywords with Arrhanius parameters at the specified pressure. This format can be used to express the pressure dependence of the rate coefficients.
```
 C3H6=C2H3+CH3                 5.986E+30  -3.9888 107791.    ! HPL
                 PLOG /    0.1 3.075E+69 -15.9470 123807.  / ! rrkm2014
                 PLOG /    1.  1.898E+71 -16.0387 128780.  /
                 PLOG /   10.  1.863E+69 -15.1393 131253.  /
                 PLOG /  100.  7.007E+61 -12.8256 128945.  /
```
The pressure (atm), A, b, Ea should be written in this order between two slashes (/ and /). The rate constants are linearly interpolated with respect to the logarithm of the pressure in between two pressure. The rate coefficients will take the lowest pressure value or the highest pressure value when the pressure is outside the specified range.

Senkin inputs

For the complete description of the Senkin input file format, See the following document.

'SENKIN: A Fortran Program for Predicting Homogeneous Gas Phase Chemical Kinetics with Sensitivity Analysis,' A. E. Lutz, R. J. Kee, and J. A. Miller, Sandia Report, SAND87-8248 (1995).

Sample input

A sample input is shown below.
```
SENS
CONP
PRES 1.0
TEMP 1000.
TIME 2.E-4
DELT 1.E-4
REAC H2  2
REAC O2  1
REAC N2  4
END
```
Place one keyword per line. Lines beginning with '.' (period), '/' (slash), or '!' (exclamation mark) are skipped as comments. Place 'END' indicating the end of input in the last line. Space character cannot be inserted at the beginning of a line.

Sensitivity option

To perform the sensitivity analysis, place 'SENS' in the first line. When no sensitivity analysis is needed, the problem selection keyword described below will appear at the first line.

Problem selection

One (and only one) of the problem selection keyword is necessary at the first input except for the 'SENS' keyword. The acceptable keywords are as follows.

CONP	CONstant Pressure & adiabatic
CONV	CONstant Volume & adiabatic
CONT	CONstant Temperature & constant pressure
ICEN	Internal Combustion ENgine (zero-dimensional) – Adiabatic compression and expansion with a constant speed crank-piston mechanism.
CGME	Core Gas Model Extention – Core gas model calculation for a rapid compression machine.
PRGV*	PRoGrammed Volume & adiabatic
VTIM^#	Volume as a function of TIMe & adiabatic
PRGT*	PRoGrammed Temperature & constant pressure
TTIM^#	Temperature as a function of TIMe & constant pressure

* ICEN, CGME, and PRGT are extended keywords which are not valid in the original Senkin.

^# When the 'VTIM' or 'TTIM' is specified, the soubroutine VOLT or TEMPT in the senkin driver (skdriver.f) must be properly written so as it calculates the volume or the temperature, respectively, at a given time.

The keywords below may be placed at any line between the problem selection keyword and 'END'.

Initial conditions

The following keywords can be used to specify the initial consitions (required).

TEMP	Initial temperature [K]
PRES	Initial pressure [atm]
REAC	Name of the reactant and moles. May present as many as needed. The name must be registered in the Species Block of chem.inp. The mole fractions will be normalized in senkin.

Integration control

The following keywords can be used to control the integration (required).

TIME	Final time [s] for integration
DELT	Time interval [s] for the console and tign.out output. In save.bin, irrespective of this parameter, results for all integration steps are stored.

Options

Keywords for restart, precision of the integration, etc. Use if required.

REST	Restart The initial condition will be read from the rest.bin. The keywords TEMP, PRES, and REAC are no longer necessary and are ignored if present.
TRES	Initial time [s] for restart Usually, the initial time for restart is read from the rest.bin. This may be changed by the 'TRES' keyword.
ATOL	Absolute tolerance of variables. It should be noted that the mass fraction of chemical species is integrated in the senkin. Default is 1E-20.
RTOL	Relative tolerance of variables. (Default : 1E-8)
ATLS RTLS	Absolute and relative tolerance of sensitivity coefficients, respectively. (Default : 1E-5)
TLIM	Ignition criterial temperature (Default : initial temperautre + DTLM [see below])
DTLM	Ignition criterial temperature increment (Default : 400 K)

MIX0D exntended options

These options can be used to investigate the gas-liquid mixing during the spray combustion and various gas-gas mixing during combustion processes by zero-dimensional calculations. These codes have been develop to analyze the reactions and ignition behaviors of the local gas mixture during the complex mixing processes occurting in the combustion including the spray combustion. They can be used with any of the problem selections (CONP, CONV, ICEN, etc.). The thremodynamics of the mixing process is calculated according to the problem selected. That is, for the volume-specified problems (CONV, ICEN, CGME, PRGV, and VTIM), the internal energy conservation is assumed, while the enthalpy conservation is assumed for the pressure-specified problem (CONP). For the temperature-specified problems (CONT, PRGT, and TTIM), isothermic mixing is assumed.

LQNF	LiQuid of Non-Fuel Option to specify that the liquid injected by INJL is non-fuel. With this option, the amount of injection specified by INJL is regarded as mass fraction to the whole system, not in terms of equivalence ratio.
INJL t_inj τ φ f_inj	INJection of Liquid Inject liquid to reacting gas to simulate the local gas behavior during the spray combustion. The temperature and the composition of the gas are calculated by assuming prompt vaporization of the liquid, according to the problem selected. With this keyword, the time to start the injection (t_inj [s]), period (τ [s]), amount of fuel injected in terms of equivalence ratio (φ),function form of the temporal injection rate profile ( f_inj) must be specified. The names of the liquid species, corresponding vapor species, and the mole fraction must be specified with the LIQU option described below. The temperature of the liquid can be specified with TLIQ option. Multiple injections can be simulated with multiple INJL option lines. The temporal injection rate profile should be one of the following three. (k = τ⁻¹) REC (RECtangular) : f = k [0, τ) EXP (EXPonential) : f = k e^{−k t} [0, ∞) RND (Rise aNd Decay) : f = k²t e^{−k t} [0, ∞) example: INJL 1e-3 2e-5 0.2 EXP INJL 3e-3 2e-5 0.2 RND
LIQU N_liq N_vap x_m	LIQUid composition Specify the chemical species name of the liquid component (N_liq) injected by INJL, the species name of the corresponding vapor (N_vap), and the mole fraction of the component (x_m). Both species should be declared in the `species` block of the Chemkin intepreter input and the thermodynamic data for them must be present. Mixture fuels such as PRF can be specified by using multiple LIQU lines as in the following example. The sum of the mole fractions does not need to be unity. It is renormalized to be unity inside the code. example-1: ! PRF90 mixture LIQU iC8H18(L) iC8H18 0.888729 LIQU nC7H16(L) nC7H16 0.111271 example-2: ! n-heptane LIQU nC7H16(L) nC7H16 1
TLIQ T_liq	Temperature of LIQuid Specify the temperature of the liquid (T_liq [K]) injcted by INJL. The default value is 323.15 K when this option is missing. example: ! 50 degree-C TLIQ 323.15
GSNE	GaS mixing Neglecting Energy equation Option to neglect the temperature (energy) of the gas mixed by MIXG. With this option, the temperature change is avoided by MIXG and only the chemical effect can be calculated.
MIXG t_st τ y f_mx N_f	MIX Gas Adiabatically mix a gas mixture with arbitrary composition and temperature. The time to start mixing (t_st [s]), period (τ [s]), mass fraction to mix (y), time-function form (f_mx), and the name of a senkin binary (restart) file (N_f) must be specified. The information of the gas to be mixed should be prepared in a senkin binary (restart) file. By using multiple MIXG option lines, same or different gas mixture(s) can be mixed multiple times. The function form of the temporal mixing rate f_mx can be selected from REC, EXP, and RND similarly to the injection rate function f_inj in INJL described above. The senkin binary (restart) files can be generated by tools such as sbrest, sbdump, sbgen, sbmod, sbhmix, etc. (See Programs overview for details.) example: MIXG 2e-3 2e-5 0.1 REC unburntgas.bin MIXG 5e-3 5e-5 0.1 REC burntgas.bin

ICEN options

When the 'ICEN' is selected for the problem, the following options may be specified. For details, see ICEN Extension to SENKIN Code (pdf).

CMPR K	Compression Ratio Ratio of the maximum cylinder volume to minimum volume. Default is 18.4
RPM N	Rotation speed [rpm] (Default : 1500)
LOLR R	Ratio of connecting rod length to crank radius (Default : 3)
VOLC V_c	Clearance volume [cm³] Cylinder volume at the TDC (top dead center). When no heat loss is considered, this value does not affect the calculation essentially, except for the output of the total mass. (Default : 100 cm³)
DEG0 θ₀	Initial crank angle [Unit: degree / TDC = 0] (Default : 180°)
ICHT a m n B T_w	Heat loss parameters Give the coefficients for the relation of Nusselt number with the Reynolds and Prandtl numbers, Nu = a Re^m Prⁿ cylinder bore, B [cm], and cylinder wall temperature, T_w [K]. It should be noted that the cylinder surface area is calculate by using V_c.

CGME options

When the 'CGME' is selected as a problem, the following optional parameters may be specified.

CCVF c₁ k₁ c₂ k₂ c₃ k₃

Parameters for the volume change after the compression
(Core-Gas Model Coefficients for Volume Function)

The virtual volume change after compression by core gas model is approximated by the following empirical equation.

V⁻¹ ∝ c₁exp(−k₁t) + c₂exp(−k₂t) + c₃exp(−k₃t) + 1

Note that only the relative change of volume is needed and the last term can always be given as unity. The unit of k_i is s⁻¹. When the following CCVC option is NOT specified, the calculation starts from the temperature and pressure of the compressed gas specified by TEMP and PRES.

CCVC t₁ V₁ t₂ V₂ t₃ V₃ t₄ V₄

Parameters for the volume change during the compression
(Core-Gas Model Coefficients for Volume Change during Compression)

The virtual volume change during the compression by core gas model is approximated by the following empirical equations.

t < 0 :	V = 1
0 ≤ t < t₁ :	V⁻¹ = b₁t² + 1	b₁ = (V₁⁻¹ − 1) / t₁²
t₁ ≤ t < t₂ :	V = b₂(t − t₁) + V₁	b₂ = (V₂ − V₁) / (t₂ − t₁)
t₂ ≤ t < t₃ :	V⁻¹ = b₃(t − t₂) + V₂⁻¹	b₃ = (V₃⁻¹ − V₂⁻¹) / (t₃ − t₂)
t₃ ≤ t < t₄ :	V⁻¹ = b₄(t − t₄)² + V₄⁻¹	b₄ = (V₃⁻¹ − V₄⁻¹) / (t₃ − t₄)²
t₄ ≤ t :	V = b₅ / [c₁exp(−k₁t') + c₂exp(−k₂t') + c₃exp(−k₃t') + 1] where t' = t − t₄	b₅ = V₄(c₁ + c₂ + c₃ + 1)

The parameters for the valume change after the compression (c₁ ~ c₃, k₁ ~ k₃) are also used, and should also be specified by the CCVF option.

In these equations, the volume is the core-gas model volume divided by the initial volume before compression. It should be unity (1) at time = 0. The unit of the time t is s [second]. When this option is specified, the initial temperature (TEMP) and pressure (PRES) should be those before the compression.

The profile of the volume change specified by the CCVC and CCVF options is shown in the figure to the right. CCVC option specifies (t_i, V_i) pairs at the switching points of the function forms. The time = 0 should be defined so that the V⁻¹ in the first part can be well approximated by a quadratic. In the second and third parts, V and V⁻¹ are approximated by straight lines, respectively. In the fourth part, V⁻¹ is quadratic. After t₄, V⁻¹ is approximated by the decay function specified by CCVF.

PRGV option

When the 'PRGV' is selected as a problem, the following optional parameter may be specified.

VPNT t V

Volume Point

Gives the volume V [cm³] at the time t [s]. The volume profile can be specified by using multiple 'VPNT' options. With PRGV extension, the volume between points are given by linear interpolation. When no volume is specified at time = 0, the default volume at time = 0 is one (1) [cm³]. The time t of this option cannot be negative.

PRGT option

When the 'PRGT' is selected as a problem, the following optional parameter may be specified.

TPNT t T

Temperature Point

Gives the temperature T [K] at the time t [s]. The temperature profile can be specified by using multiple 'TPNT' options. With PRGT extension, the temperatures between points are given by linear interpolation. The temperature at time = 0 is always the temperature specified by the 'TEMP' keyword. Therefore, the time t of this option cannot be 0 or negative.

Senkin binary-CSV coverter input

Example input

An example input is shown below.
```
===== sb2c (sbin2csv.f) Control file =====
[ TIME OUTPUT CONTROL:  (s ms us) atol=# rtol=# mind=# maxd=# sent=# ]
 us mind=1e-6 maxd=1e-5 atol=1e-15 rtol=.05
[ CONC OUTPUT CONTROL:  all selonly none molecules/cc molefrac ]
 molecules/cc selonly
 H O OH HO2 H2 O2
[ SENS OUTPUT CONTROL:  all none (or species name list) ]
 H O TEMP
```
In three blocks (TIME OUTPUT CONTROL, CONC OUTPUT CONTROL, SENS OUTPUT CONTROL), specify the control parameters. The first line and the lines beginning with '[' are comment lines and may be modified, but should not be deleted. Though the keywords are case insensitive, the species names are case sensitive.

TIME OUTPUT CONTROL (one line)

Specify the unit of the time output and the frequency of the output. Although the save.bin contains the all the results for every integration steps, they are not always necessary, for example, for the plotting. Since the converting all the time steps into CSV files often results in an extremely large file size and/or slow plotting, they are skipped properly. The skipping is controlled by the parameters here. When the variation of the variables (mostly concentrations) is small, the output interval may be large. Such a control can be done with atol and rtol. Also, for example for plotting, the resolution of the abscissa is limited to certain value. The minimum time resolution is controlled by mind.
One of the followings can be specified as the unit of time. When omitted, default is 's' (seconds).

s seconds

ms milliseconds

us microseconds

Following output controls can be specified.

atol	Absolute tolerance The species with mole fractions less than `atol` is not considered for the output frequency control. For example, with `atol=1e-15`, species with mole fraction less than 1×10⁻¹⁵ are ignored in the output frequency determination. If omitted, default is 1.0E-16.
rtol	Relative tolerance The output is done when the relative change of the any of the variable exceeds `rtol` from the last output. For example, `rtol=.05` sets the relative torelance to be 5%. If not specified, default is 0.1 (10%).
mind	Minimum Δt (Unit: seconds) Irrespective of `atol` or `rtol`, the output interval is controlled to be larger than or equal to `mind`. For example, `mind=5e-6` forces the minimum output interval to be 5 microseconds. When omitted, dafault value 1.0E-05 (10 microseconds) is adopted.
maxd	Maximum Δt (Unit: seconds) Irrespective of `atol` or `rtol`, the output interval is controlled to be smaller than or equal to `maxd`. It should be noted that the minimum output interval is determined by the internal time integration step. When omitted, dafault value 1.0E+03 (1000 seconds) is adopted.
sent	Time for sensitivity output (Unit: seconds) Sensitivity output is generated for the all time points that satisfy the other output control options without this option. When this option is specified, the sensitivity output is generated only for the specified time point.

CONC OUTPUT CONTROL (one or two line[s])

Specify the unit of concentration output and the species to be output. The following units can be accepted. (Default : molecules/cc).

molecules/cc molecules cm⁻³

molefrac mole fraction
One of the following species output control can be specified. (Default : 'all').

none none (output is generated for temperature and pressure)

selonly selected species only

all all the species
The second line is allowed only when the selonly is specified in the first line. List the name of species delimied by spaces in the second line. In the example above, concentrations of only H, O, OH, HO2, H2, and O2 are output in molecules cm⁻³ unit.

SENS OUTPUT CONTROL (one line)

Specify none, all as below, or list the variable names delimited by spaces. Variable names are the speceis names or 'TEMP' (temperature). In the example above, sensitivity coefficients are output for the species H and O, and temperature. Though this input is meaningful only when the 'SENS' is specified in senk.inp, but should never be deleted in other cases. (leave 'none', for example.)

none no output

all output for all the variables

Rxn Contrib tool input

Example

Below is an example.
```
===== rxnc (rxncntrb.f) Control Input File =====
[ (Time points to be investigated in s) time1, time2, ... ]
 2.5e-4 1.78e-4 5e-5 1.e-6
[ (species to be investigated) name1, name2, ... ]
 H O HO2
[ options (atol, min%, top#, sbin, ocsv) ]
 atol=1e-20 min%=0.1 sbin=save.bin
```
The third, fifth, and seventh lines specifies the time, species, and option, respectively. In the time specification, the time to be analyzed is specified in the unit of seconds. Multiple values are allowed. In the species line, the names of the chemical species must be listed.

In the option line, following input with the form of keyword=value can be accepted.

sbin=file name	specifies the file name of the senkin binary to be read. Default is save.bin.
top#=n (integer)	List the top n reactions with highest contribution.
min%=r (real)	List the reactions with the contribution no less than r %.
atol=ATOL	Input the same number as in the senkin input. Default is the default adopted by senkin, that is, 1E-20.
ocsv	When this option is specified, the contribution output is also generated in the .csv files.

Thermodynamic data

For the complete description of the thermodynamic data format, See the following document.

'The Chemkin Thermodynamic Data Base,' R. J. Kee, F. M. Rupley, and J. A. Miller, Sandia Report, SAND87-8215B (1994).

Thermodynamic functions are represented with the NASA polynomials,
(11)
(12)
(13)
Usually, two sets of the coefficients are prepared for two temperature ranges, 300~1000 K and 1000~5000 K. The thermodynamic data consist of a₁, a₂, ..., a₇ for high temperature and those for low temperature (totally 14 coefficients). The first line consist of the name of the chemcial species, chemical formula etc. For details, see the document shown above. Below is an example.
```
AR                120186AR  1               G  0300.00   5000.00  1000.00      1
 0.02500000E+02 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00    2
-0.07453750E+04 0.04366000E+02 0.02500000E+02 0.00000000E+00 0.00000000E+00    3
 0.00000000E+00 0.00000000E+00-0.07453750E+04 0.04366000E+02                   4
```

Chemkin-II inputs

Contents