The Beta Function of N = 1 SQED and the NSVZ Relation at the Four-Loop Level

In this article we obtained the four-loop β-function in N = 1 SQED with $${{N}_{{\text{f}}}}$$ flavours regularized by higher derivatives using a special method of calculating vacuum supergraphs. To obtain contributions to the β-function from vacuum graphs we used a C++ computer program. Final result was compared with the anomalous dimension in previous order calculated earlier.