Source code for pestifer.util.units

# Author: Cameron F. Abrams, <cfa22@drexel.edu>
from scipy.constants import physical_constants, Avogadro
import numpy as np

_SYMBOLS_ = {
    'ANGSTROM': 'Å',
    'CUBED': '³',
    'SQUARED': '²'
}
_UNITS_ = {
    'SQUARE-ANGSTROMS': f'{_SYMBOLS_["ANGSTROM"]}{_SYMBOLS_["SQUARED"]}',
    'CUBIC-ANGSTROMS': f'{_SYMBOLS_["ANGSTROM"]}{_SYMBOLS_["CUBED"]}',
    }

g_per_amu = physical_constants['atomic mass constant'][0] * 1000
A_per_cm = 1.e8
A3_per_cm3 = A_per_cm**3
cm3_per_A3 = 1.0/A3_per_cm3
n_per_mol = Avogadro


[docs]
def nmolec_in_cuA(MW_g: float, density_gcc: float, volume_A3: float) -> int:
    """
    Calculate the number of molecules in a given volume in cubic Angstroms.

    Parameters
    ----------
    MW_g : float
        Molecular weight in grams per mole.
    density_gcc : float
        Density in grams per cubic centimeter.
    volume_A3 : float
        Volume in cubic Angstroms.

    Returns
    -------
    int
        Number of molecules in the specified volume.
    """
    return int(np.floor(density_gcc/MW_g*cm3_per_A3*n_per_mol*volume_A3))



[docs]
def cuA_of_nmolec(MW_g: float, density_gcc: float, nmolec: int) -> float:
    """
    Calculate the volume in cubic Angstroms of a given number of molecules.

    Parameters
    ----------
    MW_g : float
        Molecular weight in grams per mole.
    density_gcc : float
        Density in grams per cubic centimeter.
    nmolec : int
        Number of molecules.

    Returns
    -------
    float
        Volume in cubic Angstroms.
    """
    return nmolec/(density_gcc/MW_g*cm3_per_A3*n_per_mol)