“…We choose one of the parameters, say the k th parameter, randomly with a probability p m for mutation. The mutation induces a small change in the chosen parameter ( R k ) in the following manner: R k ′ = R k + ( − 1 ) l Δ m r where l is a random integer, r is a random number in the range (0, 1), and Δ m is a directed mutation intensity (see later). The mutated string s ( R 1 , R 2 , R 3 , ..., R k ′ , ..., R m , ..., R M ) is used to generate the π-electron Hamiltonian H e π ( R ′), which in turn generates the unitary transformation matrix U λ = e − i λ H e π ( R′ ) where λ defines the scale of the transformation.…”