arXiv:2611.14485v1 Announce Type: new Abstract: This paper presents a novel fourth-order, L-stable exponential time differencing (ETD) Runge-Kutta type scheme incorporating a dimensional splitting integrating factor method for the numerical solution of nonlinear reaction-diffusion systems. The method, ETDRK4RDP-IF, is obtained by approximating the matrix exponential operators in the classical dimensionally split ETDRK-IF scheme with an accurate fourth-order, L-acceptable rational function with real and distinct poles. The L-acceptability of the rational approximation guarantees effective damping of spurious oscillations arising from nonsmooth initial and/or boundary data and further eliminates complex arithmetic in the solution of the associated linear systems, thereby enhancing computational efficiency and making the scheme well-suited for parallel implementation in low-level programming languages such as Fortran and C++. Numerical experiments confirm the fourth-order accuracy for a range of reaction-diffusion problems with Dirichlet and Neumann boundary conditions, and demonstrate that it outperforms existing standard ETD methods in serial and parallel implementations, yielding CPU time reductions of up to a factor of 20.