Physical unit definitions

Defines

Unit

This file contains definitions of various physical units. We have decided to make the units more explicit in the program; since they are inline constexpr, there should be no runtime overhead on its use, and it makes for a less bug-prone and more clear code. It also makes switching scales far easier and less bug-prone.

namespace mdk

Variables

Unit f77unit = 1.0

Unit angstrom = f77unit / 5.0

Unit nanometer = 10.0 * angstrom

Unit meter = nanometer * 1.0e9

Unit nanosecond = 1.0

Unit tau = 1.0 * nanosecond

Unit microsecond = nanosecond * 1.0e3

Unit millisecond = nanosecond * 1.0e6

Unit second = nanosecond * 1.0e9

Unit atom = 1.0

Unit mol = 6.02214076e23 / atom

Unit eps = 1.0

Unit kcal = eps * mol / 1.57824959

Unit Joule = kcal / 4184.0

Unit eps_kB = 1.0

Unit kB = eps / eps_kB

Unit Kelvin = 1.380649e-23 * Joule / kB

Unit kg = Joule * second * second / (meter * meter)

Unit au = kg * 0.99999999965e-3 / mol

Unit f77mass = eps * tau * tau / (f77unit * f77unit)

In the Fortran version of the model, distance of f77unit, time of tau, energy of eps and the average mass of an aminoacid were units; these are however incongruent, it’s a confirmed bug.

Unit echarge = 1.0

Unit Coulomb = echarge / 1.602176634e-19

Unit Ampere = Coulomb / second

Unit cspeed = 299792458.0 * meter / second

Unit Henry = kg * meter * meter / (second * second * Ampere * Ampere)

Unit mu_0 = 1.25663706212e-6 * Henry / meter

Unit epsilon_0 = 1.0 / (mu_0 * cspeed * cspeed)

Unit rad = 1.0

Unit degree = (2.0 * M_PI / 360.0) * rad