A computer-simulation study of the `white-line effect' in diffraction patterns of mixed charge-transfer salts

Computer simulations have been carried out to test the theory of the origin of the `white-line effect' in diffraction patterns of some mixed charge-transfer salts put forward by Ravy, Pouget & Comés (1992) [J. Phys. I France, 2, 1173-1190]. The diffraction patterns shown confirm that the pinning of charge-density waves to defects is responsible for the effect. The magnitudes of the atomic displacements, which were assumed to be small in development of the theory, are shown to be crucial for the effect to be observed. For displacements of ~0.008 Å, the phenomena are clearly visible, but for magnitudes of only ~0.08 Å they become masked by higher-order diffraction effects.