Physical constants, conversion factors, and a periodic table with clear source information for every value. Data from NIST CODATA 2022, Pubchem, and Washington University. All data in atomic units (e.g., length in Bohr).
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, Cordero 2008, Pyykkö 2009, Alvarez 2013 | Periodic Table, Raw CSV Data, Cordero 2008, Pyykkö 2009, Alvarez 2013 |
Solvent Data |
University of Washington | Solvent Properties |
python -m pip install qcconstTop-level constants can be accessed at attributes on the constants module for easy discovery and TAB-completion in Jupyter Notebooks or IDEs. This is the most convenient way to access constants. Most values come directly from CODATA (or are conversion factors computed directly from CODATA) that are given more computationally-friendly names for easy access.
>>> 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
...The full CODATA 2022 set of constants are available by their NIST-given name at constants.phys or constants.codata2022. constants.phys will always point to the latest CODATA values. Currently this is the 2022 release.
>>> from qcconst import constants
>>> constants.phys['atomic unit of permittivity']
1.1126500562e-10, unit=kg m s^-1, source=CODATA 2022: https://physics.nist.gov/cuu/Constants/Table/allascii.txt
>>> constants.codata2022['conventional value of von Klitzing constant']
25812.807, unit=ohm, source=CODATA 2022: https://physics.nist.gov/cuu/Constants/Table/allascii.txt>>> from qcconst import periodic_table as pt
>>> pt.Ni
Element(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)
Element(symbol='Be', number=4, name='Beryllium', mass=9.012183, group=2, period=2, block='Alkaline earth metal', electron_config='[He]2s2')
>>> pt.group(1)
[Element(symbol='H', number=1, name='Hydrogen', mass=1.00784, group=1, period=1, block='s', electron_config='1s1'),
Element(symbol='Li', number=3, name='Lithium', mass=6.94, group=1, period=2, block='s', electron_config='[He] 2s1'),
Element(symbol='Na', number=11, name='Sodium', mass=22.98976928, group=1, period=3, block='s', electron_config='[Ne] 3s1'),
Element(symbol='K', number=19, name='Potassium', mass=39.0983, group=1, period=4, block='s', electron_config='[Ar] 4s1'),
Element(symbol='Rb', number=37, name='Rubidium', mass=85.4678, group=1, period=5, block='s', electron_config='[Kr] 5s1'),
Element(symbol='Cs', number=55, name='Cesium', mass=132.90545196, group=1, period=6, block='s', electron_config='[Xe] 6s1'),
Element(symbol='Fr', number=87, name='Francium', mass=223.0, group=1, period=7, block='s', electron_config='[Rn] 7s1')]
>>> pt.period(3)
[Element(symbol='Na', number=11, name='Sodium', mass=22.9897693, group=1, period=3, block='Alkali metal', electron_config='[Ne]3s1'),
Element(symbol='Mg', number=12, name='Magnesium', mass=24.305, group=2, period=3, block='Alkaline earth metal', electron_config='[Ne]3s2'),
Element(symbol='Al', number=13, name='Aluminum', mass=26.981538, group=13, period=3, block='Post-transition metal', electron_config='[Ne]3s2 3p1'),
Element(symbol='Si', number=14, name='Silicon', mass=28.085, group=14, period=3, block='Metalloid', electron_config='[Ne]3s2 3p2'),
Element(symbol='P', number=15, name='Phosphorus', mass=30.973762, group=15, period=3, block='Nonmetal', electron_config='[Ne]3s2 3p3'),
Element(symbol='S', number=16, name='Sulfur', mass=32.07, group=16, period=3, block='Nonmetal', electron_config='[Ne]3s2 3p4'),
Element(symbol='Cl', number=17, name='Chlorine', mass=35.45, group=17, period=3, block='Halogen', electron_config='[Ne]3s2 3p5'),
Element(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
['Alvarez 2013: https://doi.org/10.1039/C3DT50599E', 'Pyykkö et al. 2009: https://doi.org/10.1002/chem.200901472', 'PubChem: https://pubchem.ncbi.nlm.nih.gov/periodic-table', 'Cordero et al. 2008: https://doi.org/10.1039/b801115j']
# Human readable print out of the Periodic Table data
>>> pt.show()
Sources: ['Pyykkö et al. 2009: https://doi.org/10.1002/chem.200901472', 'Cordero et al. 2008: https://doi.org/10.1039/b801115j', 'Alvarez 2013: https://doi.org/10.1039/C3DT50599E', 'PubChem: https://pubchem.ncbi.nlm.nih.gov/periodic-table']
symbol number name mass group period block electron_config electronegativity atomic_radius cov_radius cov_radius_double cov_radius_triple vdw_radius
------ ------ ------------- ------ ----- ------ --------------------- --------------------------------- ----------------- ------------- ---------- ----------------- ----------------- ----------
H 1 Hydrogen 1.008 1 1 Nonmetal 1s1 2.2 2.2677 0.58582 2.2677
He 2 Helium 4.0026 18 1 Noble gas 1s2 2.6456 0.52912 2.7023
Li 3 Lithium 7 1 2 Alkali metal [He]2s1 0.98 3.4393 2.4188 2.3433 4.0062
Be 4 Beryllium 9.0122 2 2 Alkaline earth metal [He]2s2 1.57 2.8913 1.8141 1.7008 1.6063 3.7417
B 5 Boron 10.81 13 2 Metalloid [He]2s2 2p1 2.04 3.6283 1.5874 1.474 1.3795 3.6094
C 6 Carbon 12.011 14 2 Nonmetal [He]2s2 2p2 2.55 3.2125 1.4362 1.2661 1.1338 3.3448
N 7 Nitrogen 14.007 15 2 Nonmetal [He] 2s2 2p3 3.04 2.9291 1.3417 1.1338 1.0205 3.1369
...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 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! ✨
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