Campo de força (química): diferenças entre revisões
Conteúdo apagado Conteúdo adicionado
Linha 12:
em que os componentes das contribuições covalentes e não covalentes são dadas pelos seguintes somatórios:
<math>\ E_{\text{ligados}} = E_{\text{
<math>\ E_{\text{não-ligados}} = E_{\text{
▲The bond and angle terms are usually modeled by quadratic energy functions that do not allow bond breaking. A more realistic description of a covalent bond at higher stretching is provided by the more expensive [[Morse potential]]. The functional form for dihedral energy is highly variable. Additional, "improper torsional" terms may be added to enforce the planarity of [[aromatic]] rings and other [[conjugated system]]s, and "cross-terms" that describe coupling of different internal variables, such as angles and bond lengths. Some force fields also include explicit terms for [[hydrogen bond]]s.
The nonbonded terms are most computationally intensive. A popular choice is to limit interactions to pairwise energies. The van der Waals term is usually computed with a [[Lennard-Jones potential]] and the electrostatic term with [[Coulomb's law]], although both can be buffered or scaled by a constant factor to account for electronic [[polarizability]] and produce better agreement with experimental observations.
| |||