Constants¶ Constants (like hbar) related to quantum mechanics. class sympy.physics.quantum.constants.HBar[source]¶ Reduced Plank’s constant in numerical and symbolic form [R755]. Examples >>> from sympy.physics.quantum.constants import hbar >>> hbar.evalf() 1.05457162000000e-34 References [R755] (1,2) https://en.wikipedia.org/wiki/Planck_constant