3.2 Basic options

Here following the complete set of options employed in krome. For additional and clearer explanation we refer to the krome paper available on ArXiV http://arxiv.org/abs/1311.1070.

Solver related options

-iRHS this option uses an implicit coding for the RHS instead the explicit one, which is the default. This issue is discussed in detail in the Krome paper. It is very useful for large systems (>500 reactions to save time during the compilation).

-forceMF=21 forces the MF value of the solver to the value 21 which means that the Jacobian and the sparsity matrix is not calculated by the solver but is explicitly determined by krome and passed to the solver at run-time.

-forceMF=222 it forces the MF value of the solver to 222 which means that the Jacobian and the sparsity matrix are calculated by the solver at runtime.

-forceRWORK=N forces the size of RWORK to the value N. This helps when krome and/or the solver have problems in determining the size of the real array employed to communicate between the solver and the routine that calls the solver.

-maxord=N forces the maximum order of integration. The default (and the largest allowed) value is 5.

-RTOL=N sets the relative tolerance of the solver to the value N. The default value is :math:10^{-4}.

-ATOL=N sets the absolute tolerance of the solver to the value N. The default value is :math:10^{-20} which ensures the stability for most of the chemical networks, even if a higher values is suggested to reduce the integration time in CPU-demanding models.

-customRTOL=FILENAME Analogous option employed for ATOL above.

-customATOL=FILENAME provides a user-defined space-separated file with the list of the ATOL for the different species. The user can indicate the explicit name of the species and the value (e.g. #H+ 1d-2#), with a species per line. The species not included in the file have ATOL equal to the default value (krome's default or indicated by the user via -ATOL option). Comments in the file are allowed (lines starting with #).

-report tracks some variables that play a key role for finding problems during the solver integration. When it is enabled the fortran code produces at run-time two files (KROME_ERROR_REPORT and KROME_ODE_REPORT) that contain the status of the system, and fortran file on unit 98 (fort.98) that dump the abundances of the species at each call of the FEX routine. Note that this option is only intended for debug purposes, since it reduce the efficiency of the code.

-useEquilibrium In most of the photoionization processes the accuracy of the solver is too low and it can generate an oscillating behaviour that may result in a solver slow down that can freeze the system.

The default krome's solver is DLSODES but we also allow users to switch on DVODE by using the following option:

-useDvodeF90 prepares the interface for the DVODE in its fortran 90.