# User’s Manual¶

The MRChem program comes as two executables:

<install-path>/bin/mrchem                   # Python input parser and launcher
<install-path>/bin/mrchem.x                 # MRChem main executable


where the former is a Python script that reads and validates the user input file and produces a new program input file which is then passed as argument to the latter, which is the actual C++ executable.

The input and output of the program is thus organized as three separate files:

File extension

Description

Format

.inp

User input file

GETKW/JSON

.json

Program input/output

JSON

.out

User output file

Text

The name of the user input file can be anything, as long as it has the .inp extension, and the corresponding .json and .out files will get the same name prefix. The JSON program file will get both an "input" and an "output" section. This "input" section is rather detailed and contains very implementation specific keywords, but it is automatically generated by the mrchem script, based on the more generic keywords of the user input file. The mrchem script will further launch the mrchem.x main executable, which will produce the text output file as well as the "output" section of the JSON in/out file. The contents of all these files will be discussed in more detail in the sections below.