6. Constants and Units

HyMD uses the following units and constants internally and in all input and output:

Units

Quantity	Symbol	Unit
length	$r$	$\text{nm}={10}^{-9}\text{m}$
time	$t$	$\text{ps}={10}^{-12}\text{s}$
charge	$q$	$e=1.602176634\cdot {10}^{-19}\text{C}$
mass	$m$	$\text{u}=1.66053906660\cdot {10}^{-27}\text{kg}$
temperature	$\text{T}$	$\text{K}$
energy	$E$	$\text{kJ}{\text{mol}}^{-1}$
velocity	$v$	$\text{nm}{\text{ps}}^{-1}={10}^3\text{m}{\text{s}}^{-1}$
momentum	$P$	$\text{u}\text{nm}{\text{ps}}^{-1}={10}^3\text{u}\text{m}{\text{s}}^{-1}$
force	$\mathbf{F}$	$\text{kJ}{\text{mol}}^{-1}{\text{nm}}^{-1}$
pressure	$p$	$\text{bar}=100\text{kPa}$
electric potential	$\mathrm{\Psi }$	$\text{kJ}{\text{mol}}^{-1}{\text{nm}}^{-1}{e}^{-1}=0.01036426965\text{V}$
electric field	$\mathbf{E}$	$\text{kJ}{\text{mol}}^{-1}{\text{nm}}^{-1}{e}^{-1}=1.03642696562\cdot {10}^7\text{V}{\text{m}}^{-1}$
compressibility	$\kappa$	$\text{mol}{\text{kJ}}^{-1}$
field-interaction	$\tilde{\chi }$	$\text{kJ}{\text{mol}}^{-1}$

Constants

Constant	Symbol	Value
gas constant	$R$	$8.3144621\cdot {10}^{-3}\text{kJ}{\text{mol}}^{-1}{\text{K}}^{-1}$
Boltzmann’s constant	$k_{\text{B}}$	$8.3144621\cdot {10}^{-3}\text{kJ}{\text{mol}}^{-1}{\text{K}}^{-1}$
Avogadro’s constant	$N_{\text{A}}$	$6.02214076\cdot {10}^{2}3{\text{mol}}^{-1}$
Vacuum permittivity	${\epsilon }_0$	$8.85418781281\cdot {10}^{-12}{\text{kg}}^{-1}{\text{m}}^{-3}{\text{s}}^4{\text{A}}^2$
Coulomb constant	$k_{\text{e}}$	$138.935458\text{kJ}{\text{mol}}^{-1}\text{nm}{e}^{-2}$