We employed ab-initio molecular dynamics to directly simulate the effects of Ag alloying (∼5 Ge_2Sb_2Te_5. The short range order is preserved, whereas a slight improvement in the chemical order is observed. A slight decrease in the fraction of tetrahedral Ge (sp^3 bonding) is reflected in the reduction of the optical band gap and in the increased dielectric constant. Simulations of the amorphous to crystalline phase change cycle revealed the fact that the crystallization speed in

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... e_5 is no less than that in Ge_2Sb_2Te_5. Moreover, the smaller density difference and the larger energy difference between the two phases of Ag_0.5Ge_2Sb_2Te_5 (compared to Ge_2Sb_2Te_5) suggest a smaller residual stress in devices due to phase transition and improved thermal stability for Ag_0.5Ge_2Sb_2Te_5. The potential viability of this material suggests the need for a wide exploration of alternative phase change memory materials.