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Overview

Table of contents

Input specification

The format of the ChronusQ input file loosely follows the INI file format commonly used in UNIX style configuration files, but has been customized for ChronusQ specifically. Most lines and keywords are case insensitive, but if they are case sensitive, it will be noted in the documentation. For example, most modern filesystems are case sensitive, so keywords that take a filesystem path are case sensitive.

In order to promote reproducibility, the input file is copied to the beginning of the output file at the beginning of the calculation.

Generally, there are 5 types of lines that an input file can contain:

  • Comment line: Begins with #
  • Section line: Contains a bracket enclosed section name, e.g. [Molecule]
  • Single line keywords: Contains a keyword definition in the form keyword = option
  • Multi-line keyword header: Contains the name of the multiline keyword in the form keyword:
  • Multi-line keyword continuation: Contains data for the most recent multiline keyword. Must be indented beyond the multiline keyword header. The exact form of this line is keyword dependent.

Graphically, this may be represented as:

# This is an example of a section definition
[Section]
var1 = value1
var2 = value2
multilinevar1:
  line1
  line2
  line3

The values in ChronusQ input may be expected to be a variety of types, listed in the table below:

Data Type Accepted formats
String Valid ASCII characters
Double precision float Decimal notation with possible exponential portion delimited by e
Integer ASCII digits
Boolean True or On (case insensitive) are true values. All other data is interpreted as false.

Supported sections

There are currently 9 supported input sections in the ChronusQ input file. Three of these sections are required for every calculation, and depending on the type of calculation, more may be required. For more information about their keywords and what they control, see the section pages specifically.

  • Molecule: Specification of molecular information such as atoms, charge, and multiplicity. Required.
  • Basis: Specification of the basis used for the calculation. Required.
  • QM: Specification of the Hamiltonian, wavefunction, and type of calculation. Required.
  • Ints: Options to control integral computation. Optional.
  • DFTInts: Options to control DFT grid evaluation. Optional.
  • SCF: Options to control SCF procedure. Optional.
  • RT: Options to control real time electron dynamics procedure. Required for RT jobs.
  • Response: Options to control response theory procedures. Required for Resp jobs.
  • Misc: Options to specify computational model. (parallelism, memory) Optional.

Example

#
#  Water RBHANDH/sto-3g / SCF parallel
#

#  Molecule Specification 
[Molecule]
charge = 0
mult = 1
geom: 
 O               0.  -0.07579184359              0.
 H     0.866811829    0.6014357793               0.
 H    -0.866811829    0.6014357793               0.

#  Job Specification
[QM]
reference = Real RBHANDH
job = SCF

# Basis Specification
[BASIS]
basis = sto-3g

# Computational Details
[MISC]
nsmp = 2
mem = 4GB

Further examples of input files are given in the Examples section of this documentation. If you would like even more examples, they can be found in the tests/<type of test>/<serial or parallel>/<type of reference> directories of the ChronusQ source code.