Comparing the performance of Monkhorst-Pack and Chadi-Cohen k-point grids

The calculation of material properties often utilizes a grid of points, known as k-points, to approximate an integral in reciprocal space. The choice of grids can greatly influence the accuracy of the calculation and its computational cost. Monkhorst-Pack grids with the shift vector of (1/2, 1/2, 1/2) are widely used due to their efficiency. However, this shift vector can break symmetry when applied to structures with trigonal or hexagonal crystal systems, which can be resolved by using a shift vector of (0, 0, 1/2). An alternative is to use Chadi-Cohen type hexagonal grids. We present a quantitative comparison of these two types of grids, looking at their performance for materials with trigonal or hexagonal symmetry. We also discuss updates to the k-point grid server such as new features and additional software package support.