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≘ 2 625.499 639 4799 (50) kJ/mol ≘ 627.509 474 0631 (12) kcal/mol ≘ 219 474.631 363 20 (43) cm −1 ≘ 6 579.683 920 502 (13) THz. where: ħ is the reduced Planck constant, m e is the electron mass, e is the elementary charge, a 0 is the Bohr radius, ε 0 is the electric constant, c is the speed of light in vacuum, and; α is the fine ...
default conversion combinations SI: yottajoule: YJ YJ 1.0 ... kcal kcal 1.0 kcal (4.2 kJ) ... Hartree: Eh (Hartree) E h: 1.0 ...
Hartree defined units based on three physical constants: [1]: 91 Both in order to eliminate various universal constants from the equations and also to avoid high powers of 10 in numerical work, it is convenient to express quantities in terms of units, which may be called 'atomic units', defined as follows:
The kilocalorie per mole is a unit to measure an amount of energy per number of molecules, atoms, or other similar particles. It is defined as one kilocalorie of energy (1000 thermochemical gram calories) per one mole of substance. The unit symbol is written kcal/mol or kcal⋅mol −1. As typically measured, one kcal/mol represents a ...
kT (also written as k B T) is the product of the Boltzmann constant, k (or k B), and the temperature, T.This product is used in physics as a scale factor for energy values in molecular-scale systems (sometimes it is used as a unit of energy), as the rates and frequencies of many processes and phenomena depend not on their energy alone, but on the ratio of that energy and kT, that is, on E ...
This Hartree–Fock model gives a reasonable description of H 2 around the equilibrium geometry – about 0.735 Å for the bond length (compared to a 0.746 Å experimental value) and 350 kJ/mol (84 kcal/mol) for the bond energy (experimentally, 432 kJ/mol (103 kcal/mol) [1]). This is typical for the HF model, which usually describes closed ...
For example, dissociation of HO−H bond of a water molecule (H 2 O) requires 118.8 kcal/mol (497.1 kJ/mol). The dissociation of the remaining hydroxyl radical requires 101.8 kcal/mol (425.9 kJ/mol). The bond energy of the covalent O−H bonds in water is said to be 110.3 kcal/mol (461.5 kJ/mol), the average of these values. [16]
Chemical accuracy is the accuracy required to make realistic chemical predictions and is generally considered to be 1 kcal/mol or 4 kJ/mol. To reach that accuracy in an economic way, it is necessary to use a series of post-Hartree–Fock methods and combine the results. These methods are called quantum chemistry composite methods. [56]