Ab initio total energy calculations are used to simulate the building of equiatomic solid APballoys (A=Li, Na, K) with A4Pb4 clusters which are particularly stable in the gas phase. Theeight clusters per unit cell wer...Ab initio total energy calculations are used to simulate the building of equiatomic solid APballoys (A=Li, Na, K) with A4Pb4 clusters which are particularly stable in the gas phase. Theeight clusters per unit cell were drawn together by shrinking the cell in stages, and allowingfull atomic relaxation at each stage. Charged Pb4 tetrahedral units dominate the structuraland electronic properties, and these units are remarkably robust and insensitive to their alkalienvironment. The stability of the Pb4 units diminishes as we progress from K to Li and lead totheir absence in the LiPb alloy in accordance with experiment. The distance between Pb4 unitsseems to be the critical factor responsible for the structural trends, which is determined by theatomic size of the alkali.展开更多
文摘Ab initio total energy calculations are used to simulate the building of equiatomic solid APballoys (A=Li, Na, K) with A4Pb4 clusters which are particularly stable in the gas phase. Theeight clusters per unit cell were drawn together by shrinking the cell in stages, and allowingfull atomic relaxation at each stage. Charged Pb4 tetrahedral units dominate the structuraland electronic properties, and these units are remarkably robust and insensitive to their alkalienvironment. The stability of the Pb4 units diminishes as we progress from K to Li and lead totheir absence in the LiPb alloy in accordance with experiment. The distance between Pb4 unitsseems to be the critical factor responsible for the structural trends, which is determined by theatomic size of the alkali.
