calculate_koopmann_energy_gradient Subroutine

public subroutine calculate_koopmann_energy_gradient(p, a, b, f, output)

this subroutine calculated the Koopmann's Theorem gradient assuming that an ionized state energy gradient is $$E_{i} = E_\text{gs} - e_i$$ or and anionic state energy is $$E_{a} = E_\text{gs} + e_a$$ it even calculates gradient for excited states assuming that $$E_{i->a} = E_\text{gs} +e_a - e_i,$$ which ignores mutual interaction between orbital a and i

Arguments

Type	Intent	Optional	Attributes		Name
type(param),	intent(in)			::	p
type(atom_set),	intent(in)			::	a(:)
type(basis),	intent(in)			::	b
type(wf_data),	intent(inout)			::	f
integer,	intent(in),	optional		::	output