get_mbd_energy Function

public function get_mbd_energy(geom, alpha_0, C6, damp, grad) result(res)

Get MBD energy.

For a nonperiodic system, the method just transforms $C_6$ coefficients to frequencies, and performs a single call to get_mbd_hamiltonian_energy. For a periodic system, the method integrates the energy over the frist Brillouin zone.

$$E=\int_\text{FBZ}\mathrm d\mathbf q\,E(\mathbf q)\approx\frac1{N_k}\sum_i^{N_k}E(\mathbf q_i) \\ \mathbf q_i=\boldsymbol{\mathcal B}\mathbf n_i,\qquad\partial\mathbf q_i=-\big((\partial\boldsymbol{\mathcal A})\boldsymbol{\mathcal A}^{-1}\big)^\mathrm T\mathbf q_i$$

Arguments

Type	Intent	Optional	Attributes		Name
type(geom_t),	intent(inout)			::	geom
real(kind=dp),	intent(in)			::	alpha_0(:)
real(kind=dp),	intent(in)			::	C6(:)
type(damping_t),	intent(in)			::	damp
type(grad_request_t),	intent(in)			::	grad

Return Value type(result_t)

Contents

None