Coverage for src/algolib/physics/constants.py: 100%

1# algolib/physics/constants.py 

2""" 

3CODATA-based physical constants in SI units. 

4 

5Notes 

6----- 

7- All values are provided in SI base units. 

8- `rel_unc` is the relative standard uncertainty. A value of `0.0` indicates an 

9 exact value as defined by the 2019 SI redefinition (e.g., `c`, `h`, `e`, 

10 `k_B`, `N_A`). 

11- Source label reflects the CODATA release used to curate the numbers. 

12""" 

13 

14CODATA_VINTAGE = "CODATA 2022" 

15 

16from dataclasses import dataclass 

17 

18@dataclass(frozen=True, slots=True) 

19class PhysConst: 

20 """Container for a physical constant in SI units. 

21 Parameters 

22 ---------- 

23 value : float 

24 Numerical value in SI base units. 

25 unit : str 

26 Unit string, e.g. "m s^-1", "J s", "C". 

27 rel_unc : float | None 

28 Relative standard uncertainty (e.g. ``1.5e-10``); use ``0.0`` for 

29 exact constants per the 2019 SI definitions. 

30 source : str 

31 Provenance label, e.g. "CODATA 2022". 

32 symbol : str 

33 Conventional symbol such as ``c``, ``h``, ``k_B``. 

34 """ 

35 value: float # numerical value (SI base units) 

36 unit: str # unit string, e.g. "m s^-1" 

37 rel_unc: float | None # relative uncertainty (0.0 for exact constants) 

38 source: str # provenance label, e.g. "CODATA 2022" 

39 symbol: str # conventional symbol ("c", "h", etc.) 

40 

41 

42 

43# — SI defining constants (exact since the 2019 redefinition) — 

44 

45c = PhysConst(299792458, "m s^-1", 0.0, "CODATA 2022", "c") 

46h = PhysConst(6.62607015e-34, "J s", 0.0, "CODATA 2022", "h") 

47e = PhysConst(1.602176634e-19, "C", 0.0, "CODATA 2022", "e") 

48k_B = PhysConst(1.380649e-23, "J K^-1", 0.0, "CODATA 2022", "k_B") 

49N_A = PhysConst(6.02214076e23, "mol^-1", 0.0, "CODATA 2022", "N_A") 

50 

51# Common derived/experimental constants (some with nonzero uncertainty; values shown as examples) 

52hbar = PhysConst(1.054571817e-34, "J s", 0.0, "CODATA 2022", "ħ") # derived as h / (2π); exact by definition 

53R = PhysConst(8.314462618, "J mol^-1 K^-1", 0.0, "CODATA 2022", "R") # R = N_A * k_B (exact by definition) 

54 

55# Examples with nonzero uncertainties (values are placeholders until a CODATA vintage is chosen) 

56alpha = PhysConst(7.2973525643e-3, "1", 1.6e-10, "CODATA 2022", "α") 

57m_e = PhysConst(9.1093837139e-31, "kg", 3.1e-10, "CODATA 2022", "m_e") 

58m_p = PhysConst(1.67262192595e-27, "kg", 3.1e-10, "CODATA 2022", "m_p") 

59m_n = PhysConst(1.67492750056e-27, "kg", 5.1e-10, "CODATA 2022", "m_n") 

60m_u = PhysConst(1.66053906892e-27, "kg", 3.1e-10, "CODATA 2022", "m_u") # defined as 1/12 of the mass of a 12C atom (not exact after 2019 SI) 

61 

62R_inf = PhysConst(1.0973731568157e7, "m^-1", 1.1e-12, "CODATA 2022", "R_∞") 

63a0 = PhysConst(5.29177210544e-11, "m", 1.6e-10, "CODATA 2022", "a0") 

64sigmaSB = PhysConst(5.670374419e-8, "W m^-2 K^-4", 1.5e-6, "CODATA 2022", "σ") 

65 

66# Note: After the 2019 SI redefinition, μ0 and ε0 are not exact. Prefer deriving them from α, h, c, and e; do not hard-code as exact.