蒙特卡罗模拟在材料科学中应用举例.ppt

蒙特卡罗模拟在材料科学中应用举例 扩散 晶粒形核与长大 再结晶 1、Monte Carlo Simulation of Diffusion Mechanism : Rand Walk 方均位移平方 !Monte Carlo Simulation of One Dimensional Diffusion INTEGER X,XX(1:1000,1:1000) REAL XXM(1:1000) ! X:INSTANTANEOUS POSITION OF ATOM ! XX(J,I)：X*X ,J:第几天实验,I:第几步跳跃 ! XXM(I): THE MEAN OF XX WRITE(*,*) 实验天数Jt，实验次数 Ic READ(*,*) Jt, Ic ISEED=RTC() DO J=1,Jt !第几天实验 X=0 ! 每天都是从原点出发 DO I=1,Ic !第几步跳跃 RN=RAN(ISEED) IF(RN0.5)THEN X=X+1 ELSE X=X-1 END IF XX(J,I)=X*X !记录下原子每天每次跳动后离原点的距离 END DO END DO OPEN(1,FILE=“f:\DIF1.DAT) DO I=1,Ic XXM=0.0 XXM(I)=1.0*SUM(XX(1:Jt,I))/Jt !! WRITE(1,*) I, XXM(I) END DO CLOSE(1) END 二维随机行走随机的确定 方法一、 RN=RAN(ISEED) IF(RN.LT.0.25)THEN x=x y=y-1 END IF IF(RN.LT.0.5.AND.RN.GE.0.25)THEN x=x y=y+1 END IF IF(RN.LT.0.75.AND.RN.GE.0.5)THEN x=x-1 y=y END IF IF(RN.GE.0.75)THEN x=x+1 y=y END IF ! Monte Carlo Simulation of Two Dimensional Diffusion INTEGER X,Y,XY(1:1000,1:1000) REAL XYM(1:1000) WRITE(*,*) 实验天数Jt，实验次数 Ic READ(*,*) Jt,Ic ISEED=RTC() DO J=1,Jt !第几天实验 X=0 !!! Y=0 !!! DO I=1,Ic !第几步跳跃 RN=RAN(ISEED) IF(RN.LT.0.25)THEN x=x y=y-1 else IF(RN.LT.0.5.AND.RN.GE.0.25)THEN x=x y=y+1 else IF(RN.LT.0.75.AND.RN.GE.0.5)THEN x=x-1 y=y else IF(RN.GE.0.75)THEN x=x+1 y=y END IF XY(J,I)=X*X+Y*Y END DO END DO OPEN(1,FILE=f:\DIF2.DAT) DO I=1,Ic XYM=0.0 XYM(I)=1.0*SUM(XY(1:Jt,I))/Jt !! WRITE(1,*) I, XYM(I) END DO CLOSE(1) END ! Monte Carlo Simulation of Two Dimensional Diffusion INTEGER X,XY(1:1000,1:1000),y,XN(1:4),YN(1:4),RN REAL XYM(1:1000) ! X:INSTANTANEOUS POSITION OF ATOM ! XY(J,I)：X*Y ,J:第几天实验,I:第几步跳跃 ! XYM(I): THE MEAN OF XY WRITE(*,*) 实验天数Jt，实验次数 Ic READ(*,*) Jt,Ic XN=(/0,0,-1,1/) YN=(/-1,1,0,0/) ISEED=RTC() D