Add erg, dyne units and Boltzmann constant (#28)

* Update copyright statements to 2021

* Add units erg, dyne

* Add Boltzmann constant

* Doc

Author: eduardo-rodrigues

LICENSE

@@ -1,6 +1,6 @@
 BSD 3-Clause License
 
-Copyright (c) 2018-2020, Eduardo Rodrigues.
+Copyright (c) 2018-2021, Eduardo Rodrigues.
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without

src/hepunits/constants/constants.py

@@ -15,7 +15,7 @@
 
 from math import pi
 
-from ..units.units import m, s, eplus, mole, joule
+from ..units.units import m, s, eplus, mole, joule, kelvin
 
 # -----------------------------------------------------------------------------
 # Mathematical constants
@@ -49,3 +49,6 @@
 hbarc = hbar_Planck * c_light
 
 hbarc_sq = hbarc * hbarc
+
+# Boltzmann constant (exact value, taken from PDG 2020)
+k_Boltzmann = 1.380649e-23 * joule / kelvin

src/hepunits/units/units.py

@@ -194,12 +194,14 @@
 
 electronvolt = _pre.micro * megaelectronvolt
 
+zettaelectronvolt = _pre.zetta * electronvolt
 exaelectronvolt = _pre.exa * electronvolt
 petaelectronvolt = _pre.peta * electronvolt
 teraelectronvolt = _pre.tera * electronvolt
 gigaelectronvolt = _pre.giga * electronvolt
 kiloelectronvolt = _pre.kilo * electronvolt
 
+ZeV = zettaelectronvolt
 EeV = exaelectronvolt
 PeV = petaelectronvolt
 TeV = teraelectronvolt
@@ -276,6 +278,8 @@
 
 J = joule
 
+erg = 1.0e-7 * joule
+
 # Power [M][L^2][T^-3]
 watt = joule / second
 
@@ -290,6 +294,8 @@
 
 N = newton
 
+dyne = 1.0e-5 * newton
+
 # Pressure
 pascal = newton / meter2