From:    Fred Streitz <streitz@oxide.physics.auburn.edu>
Date:    Sat Dec 21, 11:15am -0600
To:      meflan1@engr.uky.edu
Cc:      
Subject: Re: Your Message Sent on Fri, 20 Dec 1996 15:29:58 -0500 (EST)


Hi Matt,

Sorry, I completely forgot.

What I would do is identify (by atom number) which atoms I wanted to
hold rigid, and store them in a list IRIGID(NRIGID). Then, in a do loop 
somewhere after the forces are calculated, say something like

DO K = 1, NRIGID
     I=IRIGID(K)
     FORCE(1,I)=0.0
     FORCE(2,I)=0.0
     FORCE(3,I)=0.0
ENDDO

which zeros all the forces on those atoms. I have routines that do this
in the code, for use when I held boundary atoms rigid and pulled with a constant 
strain rate.

Let me know if you need more help.

Fred

---------------------------------------------------------------------
Frederick H. Streitz                            Phone: (334) 844-2943
Physics Department                                FAX: (334) 844-4613
Auburn University                  
Auburn, AL 36849-5311               email: streitz@physics.auburn.edu