[احمدعصام]

اخوتي الافاضل...السلام عليكم ورحمة الله وبركاته وبعد:
ما الفرق بين كلا من mass density ;atomic density;electronic density

[bero]

وعليكم السلام ورحمة الله وبركاته


The mass density or density of a material is defined as its mass per unit volume.

OR

Density is the concentration of matter It is the amount of mass per unit volume of a substance.


Atomic density refers to the number of atoms per unit volume. Typical units of atomic density are (number of atoms)/(barn*cm), where one barn = (10^-24 cm^2).
Atomic density should not be confused with mass density, which refers to the mass of a substance per unit volume.



The electronic density is a measure of the probability of an electron occupying an infinitesimal element of space surrounding any given point. It is a scalar quantity depending upon three spatial variables and is typically denoted as either ρ(r) or n(r). The density is determined, through definition, by the normalized N-electron wavefunction which itself depends upon 4N variables (3N spatial and N spin coordinates). Conversely, the density determines the wave function modulo a phase factor, providing the formal foundation of density functional theory.