how to grab some information from log file to make a new file

Dear Arun,

I am very sorry for that I did not understand what does the number after -A means before. I thought it represents the simulation run steps and I used big number such as 5000 or 10000 or something bigger. So I got the result which is described in my last email.

Now I know that I should use grep -A1 Step log.lammps > log.txt. Then I get a file consisted of these lines:

Step Temp PotEng KinEng TotEng Press Volume Dt dismax mytime
0 439.19409 -210493.42 3139.8513 -207353.57 6714.2378 1192740.8 4.7964295e-05 0.015 0