原子单位（a.u.）定义为：电子质量m$_e$ = 电子电荷e = Bohr半径 a$_0$ = 1

原子单位与国际单位的关系：

• 1 a.u.（长度）= a0 = 0.5291772083×10-10 m = 0.5291772083 Å
• 1 a.u.（质量）= me = 9.109534×10-31 Kg
• 1 a.u.（电荷）= e =1.6021892×10-19 C
• 1 a.u.（角动量）= 1.0545887×10-34 J·s
• 1 a.u.（力常数）= 1.5569×106 dyn/cm
• 1 a.u.（能量）= 1 Hartree = 27.2114 eV
• 1 a.u.（时间）= 2.4189×10-17 s
• 1 a.u.（偶极矩）= 2.542 Debye = 8.478×10-30 C·m
• 1 kcal/mol = 6.948×10-14 erg
• 1 Hartree = 4.36×10-11 erg = 2 Rydberg
• 1 eV = 1.602×10-12 erg
• 1 erg = 1.439×1013 kcal/mol = 6.2415×1011 eV
• 1 kcal/mol = 6.948×10-14 erg
• 1 Hartree = 4.36×10-11 erg = 2 Rydberg
• 1 eV = 1.602×10-12 erg
• 1 erg = 1.439×1013 kcal/mol = 6.2415×1011 eV
• 1 erg= 2.2937×1010 Hartree = 5.034×1015 cm-1
• 1 kJ/mol = 0.239006 kcal/mol = 120.272 K
• 1 kcal/mol = 4.184 kJ/mol = 503.217 K
• 1 eV = 23.0605 kcal/mol = 96.4853 kJ/mol = 1.16045×104 K
• 1 Hartree = 2625.500 kJ/mol = 627.510 kcal/mol = 3.15773 × 105 K