Molecular Mass Calculations
Molmass is a Python library and console script to calculate the molecular mass (average, nominal, and isotopic pure), the elemental composition, and the mass distribution spectrum of a molecule given by its chemical formula, relative element weights, or sequence.
Calculations are based on the isotopic composition of the elements. Mass deficiency due to chemical bonding is not taken into account.
Examples of valid formulas are H2O, [2H]2O, CH3COOH, EtOH,
CuSO4.5H2O, (COOH)2, AgCuRu4(H)2[CO]12{PPh3}2, CGCGAATTCGCG,
and MDRGEQGLLK.
Formulas are case sensitive and + denotes the arithmetic operator,
not an ion charge.
For command line usage run python -m molmass --help
| Author: | Christoph Gohlke |
|---|---|
| License: | BSD 3-Clause |
| Version: | 2020.6.10 |
Requirements
Revisions
- 2020.6.10
- Update elements_gui.py to version 2020.6.10.
- 2020.1.1
- Update elements.py to version 2020.1.1. Remove support for Python 2.7 and 3.5. Update copyright.
- 2018.8.15
- Move modules into molmass package.
- 2018.5.29
- Add option to start web interface from console.
- 2018.5.25
- Style and docstring fixes. Make 'from_fractions' output deterministic.
- 2005.x.x
- Initial release.
Examples
>>> from molmass import Formula
>>> f = Formula('D2O') # heavy water
>>> f.formula # hill notation
'[2H]2O'
>>> f.empirical
'[2H]2O'
>>> f.mass # average mass
20.02760855624
>>> f.isotope.massnumber # nominal mass
20
>>> f.isotope.mass # monoisotopic mass
20.02311817581
>>> f.atoms
3
>>> print(f.composition())
Element Number Relative mass Fraction %
2H 2 4.028204 20.1133
O 1 15.999405 79.8867
Total: 3 20.027609 100.0000
>>> print(f.spectrum())
Relative mass Fraction % Intensity
20.023118 99.757000 100.000000
21.027335 0.038000 0.038093
22.027363 0.205000 0.205499