Total energy

The total energy of a system is in quantum physics and thermodynamics, the energy difference between the system and its components at an infinite distance.

For example, the total energy of a molecule of the energy difference between the molecule in a particular state and the hypothetical state in which all the electrons and nuclei of which it consists, is infinitely far away from each other.

The total energy is not a descriptive measurement, but it has great importance in the quantum mechanical view of molecules and solids, their Schrödinger equations can be solved by approximation methods, such as Hartree -Fock, density functional theory, MP2,. The smaller the total energies of these approximate solutions, the closer they are to the exact solution of the differential equation, since according to the Rayleigh - Ritz principle, the total energy of the exact solution is always less than or equal to the total energy of an approximate solution.

In relativistic mechanics the total energy of a particle is the sum of its rest energy and its kinetic energy.

• Quantum physics
• Thermodynamics
• Relativity theory