Lattice dynamics of substitutional alloys through a combined vibrational and compositional expansion
A general method incorporating both vibrational and configurational degrees of freedom is proposed by expanding energy into vibrational clusters. Our approach captures vibrational properties in substitutional alloys with arbitrary atomic configurations which can serve as an accurate surrogate model for first-principles calculations. Compressive sensing is applied to robustly and accurately select the important configuration dependent force constants and determine their value by learning from first principles calculations in one shot. Unlike virtual crystal approximation which tends to overestimate lattice thermal conductivity at high concentration range. Great agreements with experimental results across all composition for PbTe-Se demonstrates our VCE method is an accurate approach to generate high fidelity potential energy surface across a wide range of alloy materials.