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The Hamiltonian of a system represents the total energy of the system; that is, the sum of the kinetic and potential energies of all particles associated with the system. . The Hamiltonian takes different forms and can be simplified in some cases by taking into account the concrete characteristics of the system under analysis, such as single or several particles in the system, interaction ...
The most general form of a 2×2 Hermitian matrix such as the Hamiltonian of a two-state system is given by = (+), where ,, and γ are real numbers with units of energy. The allowed energy levels of the system, namely the eigenvalues of the Hamiltonian matrix, can be found in the usual way.
Working from the definition, a partial solution for a wavefunction of a particle with a constant energy can be constructed. If the wavefunction is assumed to be separable, then the time dependence can be stated as e − i E t / ℏ {\displaystyle e^{-iEt/\hbar }} , where E is the constant energy.
Expressed using the Hubbard model, the Hamiltonian is made up of two terms. The first term describes the kinetic energy of the system, parameterized by the hopping integral, . The second term is the on-site interaction of strength that represents the electron repulsion.
for a system of particles at coordinates .The function is the system's Hamiltonian giving the system's energy. The solution of this equation is the action, , called Hamilton's principal function.
The expectation value of the total Hamiltonian H (including the term V ee) in the state described by ψ 0 will be an upper bound for its ground state energy. V ee is −5E 1 /2 = 34 eV, so H is 8E 1 − 5E 1 /2 = −75 eV. A tighter upper bound can be found by using a better trial wavefunction with 'tunable' parameters.
The variational theorem states that for a time-independent Hamiltonian operator, any trial wave function will have an energy expectation value that is greater than or equal to the true ground-state wave function corresponding to the given Hamiltonian. Because of this, the Hartree–Fock energy is an upper bound to the true ground-state energy ...
A Hamiltonian system is a dynamical system governed by Hamilton's equations. In physics , this dynamical system describes the evolution of a physical system such as a planetary system or an electron in an electromagnetic field .