Input file

This subroutine uses namelist method of reading input files into the source code. Each input file should consist of three groups: INPUT, BASIS and POTENTIAL. Wherever it's possible, we provide MOLSCAT's analogue names.

The INPUT group defines the most important information about each run:

• label (character) - 80-character string describing the code run.
• reduced_mass (double precision) - value of the reduced mass of the collisional system, in atomic mass units.
  MOLSCAT's analogue: ured.
• relative_energy_flag (integer) - can only take two values:
  • relative_energy_flag = 0 (default), energy is interpreted as the total energy of the colliding system; initial_level is ignored,
  • relative_energy_flag = 1, energy is interpreted as the relative kinetic energy, calculated with respect to the initial_level level in the basis.
    MOLSCAT's analogue (to some extent): ifegen.
• energy (double precision) - its interpretation depends on relative_energy_flag.
• initial_level (integer) - see relative_energy_flag.
• jtot_min, jtot_max, jtot_step (integers) - the calculations are performed from \( J_{min} = \) jtot_min to \( J_{max} = \) jtot_max with \( \Delta J = \) jtot_step. If jtot_max = -1, calculations are performed until consecutive_blocks_threshold consecutive values of total angular momentum contribute less than elastic_xs_threshold to the elastic state-to-state cross sections, and less than inelastic_xs_threshold to the inelastic state-to-state cross sections.
  MOLSCAT's analogues: jtotl, jtotu, jstep.
• r_min, r_max (double precision) - the propagation is performed from \( R_{min} = \) r_min to \( R_{max} = \) r_max. Note that there are no subroutines responsible for the extrapolation of the radial terms implemented in the code.
• r_step (double precision) - if positive, it corresponds to the step of the propagator (in \( a_{0} \) ).
• steps (integer) - number of steps per half-wavelength of de Broglie's wavefunction of the system (see variable documentation for details).
• potential_depth (double precision, 0 by default) - the user is advised to specify the absolute value of the depth of the potential energy surface, which is included in the determination of the step size of the propagator (see variable documentation for details).
  MOLSCAT's analogue: eps.
• consecutive_blocks_threshold (integer), elastic_xs_threshold, inelastic_xs_threshold (double precision), see (jtot_min, jtot_max and jtot_step).
  MOLSCAT's analogues: ncac, dtol, otol.
• number_of_basis_levels (integer) - number of levels in the basis set.
  MOLSCAT's analogue: nlevel.
• number_of_r_points (integer) - number of the grid points for the radial coupling terms in the potential expansion.
• number_of_legendre_indices (integer) - number of \( \lambda \) terms in the potential expansion, see Eq. (3) in Coupling Matrix section.
• total_number_of_coupling_terms (integer) - determines the total number of columns containing the radial coupling terms (see Supplying radial coupling terms).
• n_skip_lines (integer) - number of lines at the beginning of the radial coupling terms file, which will be ignored while reading (see Supplying radial coupling terms).
• coupling_terms_r_unit (character, "--------" by default) - if the \( R \) grid in the radial coupling terms file is given in atomic units (\( a_{0} \)), choose coupling_terms_r_unit = "bohr". If the radial distance is given in Å, put coupling_terms_r_unit = "angstrom".
• coupling_terms_file_name (character, "RadialTerms.dat" by default) - the name of the file with the radial coupling terms.
• s_matrix_file_name (character, "s_matrix_file_name.dat" by default) - the name of the s-matrix file.
• print_partial_cross_sections (logical, false by default) - if partial cross sections (for each parity block, within each \(J\)-block) are needed, put print_partial_cross_sections = true.
• partial_xs_file_name (character, "partial_xs_file_name.dat" by default) - the name of the file with partial cross sections.
• print_level (integer, 2 by default):
  • print_level = 0, basic information about a run,
  • print_level = 1, information about each block is printed on screen,
  • print_level = 2, information about the calculation time of some of the important parts of the code is printed,
  • print_level = 3, accumulated state-to-state cross sections are printed on screen after each total angular momentum block,
  • print_level \( > \) 4, S-matrices are printed on screen.
    MOLSCAT's analogue: iprint.

BASIS group specifies the vibrational and rotational quantum numbers of colliding molecules and the energy levels of rovibrational states

• vib_levels (integer array of number_of_basis_levels size) - keeps values of the vibrational (\( v \)) quantum numbers that describe the levels of a diatomic molecule.
• rot_levels (integer array of number_of_basis_levels size) - keeps values of the rotational (\( j \)) quantum numbers that describe the levels of a diatomic molecule.
• internal_energies (double precision array of number_of_basis_levels size) - keeps energies of the rovibrational levels of a diatomic molecule, in cm\( ^{-1} \).

Note that in MOLSCAT's itype = 7, pairs of rotational and vibrational quantum numbers are provided in jlevel array.

POTENTIAL group describes the quantum numbers of the radial coupling terms, \( v_{\boldsymbol{\lambda},\gamma,\gamma'} (R) \), see Eq. (3) in Coupling Matrix section. This group of variables involves:

• legendre_indices (integer array of number_of_legendre_indices size) - keeps values of \( \lambda \) indices, describing the radial terms of the potential.
• vib_couplings, rot_couplings, vib_prime_couplings, rot_prime_couplings (integer arrays of total_number_of_coupling_terms size)
• keep values of \( v, j, v', j' \) indices of the radial coupling terms of the potential.

Note that in MOLSCAT \(\lambda\) indices and quantum numbers identifying coupling terms are provided by nterm and lambda variables.