qcconst 0.1.2

Physical constants, conversion factors, and a periodic table with clear source information for every value.

QCConst

Physical constants, conversion factors, and a periodic table with clear source information for every value. Data from NIST CODATA 2022, Pubchem, and Washington University.

Data Sources

Each piece of data contains a link to its source. Primary data sources include:

Data Name	Source	Source Links
Physical Constants	NIST 2022 CODATA	Individual Constant Lookup, Fundamenal Constants Listing, Conversion Factors
Periodic Table	PubChem	Periodic Table, Raw CSV Data
Solvent Data	University of Washington	Solvent Properties

Installation

pip install qcconst

Quickstart

Constants

>>> from qcconst import constants

>>> constants.BOHR_TO_ANGSTROM
0.529177210544, unit=Å, source=https://physics.nist.gov/cgi-bin/cuu/Value?bohrrada0

# Use constants just like a float
>>> constants.BOHR_TO_ANGSTROM * 10
5.29177210544

# Know the source of every constant
>>> constants.BOHR_TO_ANGSTROM.source
'https://physics.nist.gov/cgi-bin/cuu/Value?bohrrada0'

# See sources for all constants
>>> constants.sources
['https://physics.nist.gov/cgi-bin/cuu/Value?bohrrada0', 'https://physics.nist.gov/cgi-bin/cuu/Value?hrj|search_for=hartree+to+joule', 'https://physics.nist.gov/cuu/Constants/Table/allascii.txt', 'https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8']

# List all available constants
>>> constants.as_list()
['ANGSTROM_TO_BOHR', 'AVOGADRO_NUMBER', 'BOHR_TO_ANGSTROM', 'BOLTZMANN_CONSTANT', 'HARTREE_TO_JOULE', 'HARTREE_TO_KCAL_PER_MOL', 'KCAL_TO_JOULE', ...]

# Human readable print out of all available constants
>>> constants.show()
name                              value  unit      source
-----------------------  --------------  --------  ---------------------------------------------------------
ANGSTROM_TO_BOHR            1.88973      Bohr      Derived as 1 / BOHR_TO_ANGSTROM
AVOGADRO_NUMBER             6.02214e+23  mol⁻¹     https://physics.nist.gov/cuu/Constants/Table/allascii.txt
BOHR_TO_ANGSTROM            0.529177     Å         https://physics.nist.gov/cgi-bin/cuu/Value?bohrrada0
BOLTZMANN_CONSTANT          1.38065e-23  J/K       https://physics.nist.gov/cuu/Constants/Table/allascii.txt
...

Periodic Table

>>> from qcconst import periodic_table as pt

>>> pt.Ni
Atom(symbol='Ni', number=28, name='Nickel', mass=58.6934, group=10, period=4, block='d', electron_config='[Ar] 3d8 4s2')

>>>pt.Ni.number
28

# Lookup by atomic number
>>> pt.number(4)
Atom(symbol='Be', number=4, name='Beryllium', mass=9.012183, group=2, period=2, block='Alkaline earth metal', electron_config='[He]2s2')

>>> pt.group(1)
[Atom(symbol='H', number=1, name='Hydrogen', mass=1.00784, group=1, period=1, block='s', electron_config='1s1'),
Atom(symbol='Li', number=3, name='Lithium', mass=6.94, group=1, period=2, block='s', electron_config='[He] 2s1'),
Atom(symbol='Na', number=11, name='Sodium', mass=22.98976928, group=1, period=3, block='s', electron_config='[Ne] 3s1'),
Atom(symbol='K', number=19, name='Potassium', mass=39.0983, group=1, period=4, block='s', electron_config='[Ar] 4s1'),
Atom(symbol='Rb', number=37, name='Rubidium', mass=85.4678, group=1, period=5, block='s', electron_config='[Kr] 5s1'),
Atom(symbol='Cs', number=55, name='Cesium', mass=132.90545196, group=1, period=6, block='s', electron_config='[Xe] 6s1'),
Atom(symbol='Fr', number=87, name='Francium', mass=223.0, group=1, period=7, block='s', electron_config='[Rn] 7s1')]

>>> pt.period(3)
[Atom(symbol='Na', number=11, name='Sodium', mass=22.9897693, group=1, period=3, block='Alkali metal', electron_config='[Ne]3s1'),
Atom(symbol='Mg', number=12, name='Magnesium', mass=24.305, group=2, period=3, block='Alkaline earth metal', electron_config='[Ne]3s2'),
Atom(symbol='Al', number=13, name='Aluminum', mass=26.981538, group=13, period=3, block='Post-transition metal', electron_config='[Ne]3s2 3p1'),
Atom(symbol='Si', number=14, name='Silicon', mass=28.085, group=14, period=3, block='Metalloid', electron_config='[Ne]3s2 3p2'),
Atom(symbol='P', number=15, name='Phosphorus', mass=30.973762, group=15, period=3, block='Nonmetal', electron_config='[Ne]3s2 3p3'),
Atom(symbol='S', number=16, name='Sulfur', mass=32.07, group=16, period=3, block='Nonmetal', electron_config='[Ne]3s2 3p4'),
Atom(symbol='Cl', number=17, name='Chlorine', mass=35.45, group=17, period=3, block='Halogen', electron_config='[Ne]3s2 3p5'),
Atom(symbol='Ar', number=18, name='Argon', mass=39.9, group=18, period=3, block='Noble gas', electron_config='[Ne]3s2 3p6')]

# Know the sources of the data
>>> pt.sources
['https://pubchem.ncbi.nlm.nih.gov/periodic-table']

# Human readable print out of the Periodic Table data
>>> pt.show()
Sources: https://pubchem.ncbi.nlm.nih.gov/periodic-table, https://pubchem.ncbi.nlm.nih.gov/rest/pug/periodictable/CSV?response_type=save&response_basename=PubChemElements_all

symbol      number  name                mass    group    period  block                  electron_config
--------  --------  -------------  ---------  -------  --------  ---------------------  ---------------------------------
H                1  Hydrogen         1.008          1         1  Nonmetal               1s1
He               2  Helium           4.0026        18         1  Noble gas              1s2
Li               3  Lithium          7              1         2  Alkali metal           [He]2s1
Be               4  Beryllium        9.01218        2         2  Alkaline earth metal   [He]2s2
B                5  Boron           10.81          13         2  Metalloid              [He]2s2 2p1
C                6  Carbon          12.011         14         2  Nonmetal               [He]2s2 2p2
N                7  Nitrogen        14.007         15         2  Nonmetal               [He] 2s2 2p3
...

Solvents

Solvents are accessed with a dictionary lookup rather than attribute lookup because many of their names are invalid Python attributes (i.e., they start with a number or contain - characters). For example, solvents.1,2-dimethoxyethane is invalid syntax. As a result, solvents are looked up using solvents['name'] rather than solvents.name.

from qcconst import solvents

>>> solvents["1,4-dioxane"]
Solvent(name='1,4-dioxane', dielectric=2.25, sources=['https://depts.washington.edu/eooptic/linkfiles/dielectric_chart%5B1%5D.pdf'])

>>> solvents["1,4-dioxane"].dielectric
2.25

# Will return None if solvent not found
>>> solvents.get("Fake Solvent")
>>>

# List all available solvents
>>> solvents.as_list()
['acetic acid', 'acetone', 'acetonitrile', 'anisole', 'benzene', 'bromobenzene', 'carbon disulfide', 'carbon tetrachloride', 'chlorobenzene', 'chloroform', 'cyclohexane', 'dibutyl ether', 'o-dichlorobenzene', '1,2-dichloroethane', 'dichloromethane', 'diethylamine', 'diethyl ether', '1,2-dimethoxyethane', 'n', 'n,n-dimethylformamide', 'dimethyl sulfoxide', '1,4-dioxane', 'ethanol', 'ethyl acetate', 'ethyl benzoate', 'formamide', 'hexamethylphosphoramide', 'isopropyl alcohol', 'methanol', '2-methyl-2-propanol', 'nitrobenzene', 'nitromethane', 'pyridine', 'tetrahydrofuran', 'toluene', 'trichloroethylene', 'triethylamine', 'trifluoroacetic acid', '2,2,2-trifluoroethanol', 'water', 'o-xylene', ...]

# Know the sources of the data
>>> solvents["water"].sources
['https://depts.washington.edu/eooptic/linkfiles/dielectric_chart%5B1%5D.pdf']

# Human readable print out of all available solvents
>>> solvents.show()
name                       dielectric  sources
-----------------------  ------------  ------------------------------------------------------------------------------
acetic acid                      6.15  ['https://depts.washington.edu/eooptic/linkfiles/dielectric_chart%5B1%5D.pdf']
acetone                         20.7   ['https://depts.washington.edu/eooptic/linkfiles/dielectric_chart%5B1%5D.pdf']
acetonitrile                    37.5   ['https://depts.washington.edu/eooptic/linkfiles/dielectric_chart%5B1%5D.pdf']
anisole                          4.33  ['https://depts.washington.edu/eooptic/linkfiles/dielectric_chart%5B1%5D.pdf']
benzene                          2.27  ['https://depts.washington.edu/eooptic/linkfiles/dielectric_chart%5B1%5D.pdf']
bromobenzene                     5.17  ['https://depts.washington.edu/eooptic/linkfiles/dielectric_chart%5B1%5D.pdf']
...

Adding New Values

Adding new values is simple! Just add it to one of the .csv files in src/qcconst/data. Include the value, its source, and any other required metadata and then open a PR. That's it! ✨

The QC Suite of Programs

If you like qcconst you may like my other libraries for computational chemistry.

• qcio - Elegant and intuitive data structures for quantum chemistry, featuring seamless Jupyter Notebook visualizations. Documentation
• qcparse - A library for efficient parsing of quantum chemistry data into structured qcio objects.
• qcop - A package for operating quantum chemistry programs using qcio standardized data structures. Compatible with TeraChem, psi4, QChem, NWChem, ORCA, Molpro, geomeTRIC and many more.
• BigChem - A distributed application for running quantum chemistry calculations at scale across clusters of computers or the cloud. Bring multi-node scaling to your favorite quantum chemistry program.
• ChemCloud - A web application and associated Python client for exposing a BigChem cluster securely over the internet.