Standalone CLI utilities#

This page documents selected SimpNMR command-line utilities that operate directly on input files and do not require YAML pipeline configuration files.

These commands are intended for quick calculations, post-processing, and exploratory analysis, and can be used independently of the YAML-driven workflows documented elsewhere.

calc_pcs_iso#

The calc_pcs_iso command computes isotropic pseudocontact shift (PCS) fields directly from a magnetic susceptibility tensor and a molecular structure.

This command is intentionally lightweight and does not require a YAML input file. The susceptibility backend and method are determined automatically from the input file.

Automatic method selection

If the susceptibility source is an ORCA output file, the most advanced available susceptibility method is selected automatically (e.g. NEVPT2 is preferred over CASSCF). Explicit method selection is not required.

Required input

  • A susceptibility source file (e.g. CSV file or ORCA output containing susceptibility data)

  • A temperature value (in Kelvin)

  • A molecular structure file (XYZ format)

  • The label of the paramagnetic centre (as defined in the structure file)

Typical usage

simpnmr calc_pcs_iso susceptibility.csv 298.0 structure.xyz Fe1

When an ORCA output file is provided instead of a CSV file, the susceptibility backend and method are inferred automatically from the file contents.

The command produces PCS values on a three-dimensional grid, suitable for visualisation or further analysis.

get_sh#

The get_sh command derives effective spin-Hamiltonian parameters from a previously performed magnetic susceptibility (χT) regression.

It is intended as a post-processing utility and does not perform fitting itself. No YAML configuration file is required.

Required input

  • A CSV file containing χT regression results

  • The spin quantum number of the paramagnetic centre

Typical usage

simpnmr get_sh --spin 2.0 chiT_regression.csv

The command extracts the effective g-tensor (and, if applicable, zero-field splitting parameters) from the regression data and prints the results to standard output.

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