Description:

pyvalem 2.7.1

Introduction to PyValem
PyValem is a Python package for parsing, validating, manipulating and
interpreting the chemical formulas, quantum states and labels of atoms, ions
and small molecules.
Species and states are specified as strings using a simple and flexible syntax,
and may be compared, output in different formats and manipulated using a
variety of predefined Python methods.

Installation:
The PyValem package can be installed either from PyPI using pip
python3 -m pip install pyvalem
or from the source by running (one of the two) from the project source directory.
# either
python setup.py install

# or
python3 -m pip install .


Examples:

Formula
The basic (state-less) chemical formulas are represented by the Formula class.
A Formula object is instantiated from a valid formula string and supports ions,
isotopologues, as well as a few special species.
The object contains attributes with its HTML and LaTeX representations,
and its molar mass.
>>> from pyvalem.formula import Formula

>>> # neutral formulas:
>>> Formula('C2H5OH')
C2H5OH

>>> # isotopes:
>>> Formula('(14C)')
(14C)

>>> # ions
>>> [Formula('H3O+'), Formula('(1H)(2H)+'), Formula('Co(H2O)6+2')]
[H3O+, (1H)(2H)+, Co(H2O)6+2]

>>> # special species
>>> [Formula('e-'), Formula('hv')]
[e-, hν]

>>> # formula attributes:
>>> Formula('Ar+2').charge
2

>>> Formula('H2(18O)').html
'H₂¹⁸O'

>>> print(Formula('H2(18O)').latex)
\mathrm{H}_{2}{}^{18}\mathrm{O}

>>> Formula('(235U)').mass
235.04392819


“Stateful” Species
The “stateful” species represent species with (or without) any number of states
attached.
The StatefulSpecies object can be instantiated from a valid string, which consist
of a valid Formula string, followed by a whitespace, followed by a
semicolon-delimited sequence of valid State strings.
PyValem supports several different types of state notation.
For further information on valid PyValem State strings, consult the documentation.
Examples:
>>> from pyvalem.stateful_species import StatefulSpecies

>>> stateful_species = StatefulSpecies('Ne+ 1s2.2s2.2p5; 2P_1/2')
>>> stateful_species.formula
Ne+

>>> type(stateful_species.formula)
<class 'pyvalem.formula.Formula'>

>>> stateful_species.states
[1s2.2s2.2p5, 2P_1/2]

>>> state1, state2 = stateful_species.states
>>> type(state1)
<class 'pyvalem.states.atomic_configuration.AtomicConfiguration'>

>>> state1.orbitals
[1s2, 2s2, 2p5]

>>> type(state2)
<class 'pyvalem.states.atomic_term_symbol.AtomicTermSymbol'>

>>> state2.L, state2.J
(1, 0.5)
As Formula, also StatefulSpecies have html and latex attributes.
>>> print(stateful_species.latex)
\mathrm{Ne}^{+} \; 1s^{2}2s^{2}2p^{5} \; {}^{2}\mathrm{P}_{1/2}

>>> StatefulSpecies('(52Cr)(1H) 1sigma2.2sigma1.1delta2.1pi2; 6SIGMA+; v=0; J=2').html
'⁵²Cr¹H 1σ².2σ¹.1δ².1π² ⁶Σ⁺ v=0 J=2'


Reaction
Finally, the Reaction class represents a reaction or a collisional process between
species. A Reaction object is instantiated with a string consisting of valid
Formula or StatefulSpecies strings delimited by ' + ', and reaction sides
separated by ' -> ', such as
>>> from pyvalem.reaction import Reaction
>>> reaction = Reaction('He+2 + H -> He+ 3p1 + H+ + hv')
>>> reaction
He+2 + H → He+ 3p + H+ + hν

>>> reaction.html
'He²⁺ + H → He⁺ 3p + H⁺ + hν'

>>> print(reaction.latex)
\mathrm{He}^{2+} + \mathrm{H} \rightarrow \mathrm{He}^{+} \; 3p + \mathrm{H}^{+} + h\nu
The Reaction class also watches out for charge balance and stoichiometry
conservation during instantiation.
>>> Reaction('(2H) + (3H) -> (4He)')
Traceback (most recent call last):
...
pyvalem.reaction.ReactionStoichiometryError: Stoichiometry not preserved for reaction: (2H) + (3H) -> (4He)

>>> Reaction('e- + Ar -> Ar+ + e-')
Traceback (most recent call last):
...
pyvalem.reaction.ReactionChargeError: Charge not preserved for reaction: e- + Ar -> Ar+ + e-



For Developers:
It goes without saying that any development should be done in a clean virtual
environment.
After cloning or forking the project from its GitHub page, pyvalem might be
installed into the virtual environment in editable mode with
pip install -e .[dev]
or on zsh:
pip install -e .'[dev]'
The [dev] extra installs (apart from the package dependencies) also several
development-related packages, such as pytest, black, tox or ipython.
The tests can then be executed by running (from the project root directory)
# either
pytest

# or
tox
The project does not have requirements.txt by design, all the package dependencies
are rather handled by setup.py.
The package needs to be installed to run the tests, which grants the testing process
another layer of usefulness.
Docstrings in the project adhere to the numpydoc styling.
The project code is formatted by black.
Always make sure to format your code before submitting a pull request, by running
black on all your python files.

License

For personal and professional use. You cannot resell or redistribute these repositories in their original state.

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