简介:DDRSDRAM和266MHz总线的1、1.2、1.3GHzAthlon已发布,支持这些内存和CPU的主板的上市是期待之中的事。本文将介绍华硕最近推出的两款使用最新芯片组、支持DDRSDRAM和1GHz以上Athlon的主板A7M266和A7V133。A7M266是一款采用AMD760芯片组SocKetA架构的ATX主板,可以支持以266MHz外频工作的Athlon。此外,通过调整外频的设置值,它也可以支持以往的EV6200总线的Athlon和Duron处理器。板上有2个DDRSDRAM用的DIMM插槽,用于插PC1600或PC2100内存;但要注意:当FSB为200MHz时,即使是PC2100内存也只能当PC1600内存使用。板载的最大
简介:Theequilibriumgeometries,relativestabilities,andelectronicpropertiesofMnAgm(M=Na,Li;n+m≤7)aswellaspureAgn,Nan,Lin(n≤7)clustersaresystematicallyinvestigatedbymeansofthedensityfunctionaltheory.Theoptimizedgeometriesrevealthatfor2≤n≤7,therearesignificantsimilaritiesingeometryamongpureAgn,Nan,andLinclusters,andthetransitionsfromplanartothree-dimensionalconfigurationsoccuratn=7,7,and6,respectively.Incontrast,thefirstthree-dimensional(3D)structuresareobservedatn+m=5forbothNanAgmandLinAgmclusters.Whenn+m≥5,astrikingfeatureisthatthetrigonalbipyramidbecomesthemainsubunitofLinAgm.Furthermore,dramaticodd-evenalternativebehavioursareobtainedinthefragmentationenergies,secondorderdifferenceenergies,highestoccupiedandlowestunoccupiedmolecularorbitalenergygaps,andchemicalhardnessforbothpureanddopedclusters.Theanalyticresultsexhibitthatclusterswithanevenelectronicconfiguration(2,4,6)possesstheweakestchemicalreactivityandmoreenhancedstability.