# [molpro-user] The problem about a reversed loop to optimize CH3Cl(Cs) with casscf method

Mon Sep 10 08:09:53 BST 2012

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Dear colleagues,
recently,I want to use a loop program to optimize CH3Cl(Cs) with casscf method.And
I try to use the following design:
***,ch3cl
memory,384,m;
!file,2,ch3ccl-single_point-test.wfu

basis={
spdf,c,avtz;c;
spd,h,avtz;c;
spdf,Cl,aug-cc-pV(T+d)Z;c;
}

rch2=1.1;
alpha=108.8;
beta=108.8;
delta=120;

geometry={Z;
ang;
c,
Cl,c,r1(i);
h1,c,r2(i),Cl,alpha;
h2,c,rch2,Cl,beta,h1,delta;
h3,c,rch2,Cl,beta,h2,delta;}

distance1=[1.8,1.7,1.6,1.5,1.4]
distance2=[1.1,1.0,0.9,0.8]

i=0
do ir1=1,#distance1
do ir2=1,#distance2
i=i+1
r1(i)=distance1(ir1)
r2(i)=distance2(ir2)

{hf;wf,26,1,0;}

{multi;occ,12,5;closed,5,1;
wf,26,1,0;state,2;
wf,26,2,0;state,1;
}

optg;
enddo
enddo
---

However,everytime when the "distance2"  loop is over, there is a big gap between the two configuration before and after.For example, [1.7,1.1]come after[1.8,0.8].So I want the second loop run in reverse direction when the number of first loop is even.But,the i is the total count value.So I am confused about how to use IF command to achieve my aim.
Generally speaking, I have two question:
1. the value of rch, alpha,beta and delta in next loop is the  the result of previous or not?(I mean the result of previous cycle or the initial value I set)
2. How to make the second loop run in reversed direction when the the number of first      loop is even?(I want to use IF command,but "i" is total count value.And I also don't know the command of reverse loop)
Any suggestions will be appreciated.

best regard

-kai

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