Application of the SCVT Orientation Grid to the Simulation of CW EPR Powder Spectra

The orientation grid obtained using the spherical centroidal Voronoi tessellation (SCVT) method is assessed for the simulation of continuous-wave electron paramagnetic resonance (CW EPR) powder spectra. The SCVT spherical code presents less distorted Voronoi cells associated to the points of the grid compared to the regular Igloo, SOPHE and EasySpin grids and similar distortions of the cells to the irregular Repulsion grid. The degree of distribution of the SCVT cells’ areas is smaller than for SOPHE, but higher than for the Igloo and Repulsion grids. All compared spherical codes have nearly the same electrostatic potential energy. Simulated CW EPR powder spectra for rhombic systems of spin S = 1/2 are similar when using the energy minimization SCVT and Repulsion spherical codes and show less intense ripples than the spectra calculated with the SOPHE and Igloo grids, but more intense than those obtained using the EasySpin grid. The classical projection method and a new modified form involving the spectral intensities at the orientations of the grid have been tested for the attenuation of the simulation noise, for grids of relatively reduced size.