Abstract
We have studied by the first-principles total energy method the off-center instabilityof a substitutional Li impurity in KCl. We report here the results of super-cellcalculations of the energy associated with displacing the Li along , and directions relative to the K vacancy. To understand the influence of relaxations, weperformed three levels of relaxations—only first nearest neighbors of the vacancy, first andsecond nearest neighbors, and full relaxation. Our calculations show that therelaxation significantly affects the energy surface and that the relaxation of thenearest neighbors to the vacancy accounts for most of the trend. The positionof minimum energy for the Li was found to be along the direction. The calculated well along is 102 meV deep relative to the on-center energy and lies about 0.86 Å off-center. Minimaalong adjacent directions are separated by a saddle-point barrier of 44 meV along the direction. Our calculated results are in agreement with prior model calculationsand we believe our calculated potential surfaces are the best theoretical result sofar.
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call