Basic usage¶
There are two main ways of running QSym²:
- via the command-line interface provided by the binary
qsym2
, or - via the exposed Python bindings provided by the Python library
qsym2
.
Command-line interface¶
Scope¶
This method is currently able to perform symmetry analysis of:
- Slater determinants,
- Hartree–Fock or Kohn–Sham molecular orbitals, and
- vibrational coordinates
that have been exported by Q-Chem 6 to a HDF5 file named qarchive.h5
saved in the job's scratch directory,
or
- Slater determinants, and
- Hartree–Fock or Kohn–Sham molecular orbitals
that have been stored in binary files, together with other basis-set-related data.
Instructions¶
The command-line interface supports several subcommands and options:
A program for Quantum Symbolic Symmetry
Usage: qsym2 <COMMAND>
Commands:
template
Generates a template YAML configuration file and exits
run
Runs an analysis calculation and exits
help
Print this message or the help of the given subcommand(s)
Options:
-h, --help
Print help
-V, --version
Print version
The subcommand template
, runnable as
The subcommand run
, runnable as
Examples of symmetry analysis performed by QSym² for several Q-Chem calculations can be found in the User guide.
Python interface¶
Scope¶
This method is currently able to perform symmetry analysis of:
- Slater determinants,
- Hartree–Fock or Kohn–Sham molecular orbitals,
- multi-determinantal wavefunctions obtained via non-orthogonal configuration interaction,
- real-space functions defined on a grid,
- vibrational coordinates, and
- one-electron densities
that can be computed directly in Python or read into Python from calculation files of quantum-chemistry packages, such as by the use of cclib. The main driver functions of QSym² are all exposed to Python, which means that they can be used and integrated into existing workflows flexibly.
Instructions¶
To view the documentation for the Python API, execute the following Python commands inside the qsym2-python
conda environment (see Python-library compilation), either interactively or in a Python script:
An example Python script that performs symmetry analysis for self-consistent-field calculations from Orca output files (parsed by cclib) can be found at utils/qsym2-orca.py
. This script requires the Python packages mendeleev
, cclib
, and numpy
to run.
Another example where the Python bindings of QSym² are used extensively for the analysis of unitary and magnetic symmetry in the presence of external fields can be found in QUEST and its complementary GUI, QuestView.