It is possible to eliminate the phase-lag and its first, second, and third derivatives by employing a phase-fitting technique. The new approach is called the economical method because it makes use of the highest possible algebraic order (AOR) with the fewest possible function evaluations (FEvs). The unique method can be expressed as the equation PF3DPFN142SPS. The proposed method is an infinitely periodic P-Stable approach. Many problems with periodic and/or oscillating solutions are amenable to the proposed technique. In quantum chemistry, this novel method was used to solve the difficult problem of Schrödinger-type coupled differential equations. Because the new method requires just a 5FEvs to accomplish each stage, we refer to it as an economic algorithm. This allows us to attain a 14AOR, which is a significant improvement over the status quo.