# [molpro-user] Freq calculation

samala nagaprasad reddy snpreddy63 at gmail.com
Thu Sep 17 17:31:56 BST 2015

```Hi
I have a couple of questions.

1) I am calculating optimization and frequency calculation of benzene.
After optimization when I calculate the single point energy calculation the
SP energy is lower than the optimized energy. I am taking the optimized Z
matrix to run the SP energy calculation. How it is possible? What I am
missing? Here I am giving my input of optimization and output files of both
SP and optimization calculations.

Optimization input

***,coupling constants
memory,450,m
cc2    =    1.394207,
ccc3   =    120.000,
dih4   =      0.000,
hc7    =    1.082115,
dih7   =    180.000
basis,avtz
geomtype = zmat
geometry = {angstrom,
c;
c,   1, cc2;
c,   2, cc2,        1, ccc3;
c,   3, cc2,        2, ccc3,          1, dih4;
c,   4, cc2,        3, ccc3,          2, dih4;
c,   5, cc2,        4, ccc3,          3, dih4;
h,   2, hc7,        3, ccc3,          4, dih7;
h,   3, hc7,        2, ccc3,          1, dih7;
h,   4, hc7,        3, ccc3,          2, dih7;
h,   5, hc7,        4, ccc3,         3, dih7;
h,   6, hc7,        5, ccc3,         4, dih7;
h,   1, hc7,        2, ccc3,         3, dih7;
}
{hf,ENERGY=1.0E-10,orbital=1.0E-8;}
{df-hf,ENERGY=1.0E-10,orbital=1.0E-8;}
{df-mp2,ENERGY=1.0E-10,orbital=1.0E-8;}
optg;
frequencies;

SP energy input

! Cite this work as:
***,coupling constants
memory,450,m
cc2    =    1.394247,
cc3    =    1.394247,
ccc3   =    120.000,
cc4    =    1.394247,
ccc4   =    120.000,
dih4   =      0.000,
cc5    =    1.394247,
ccc5   =    120.000,
dih5   =      0.000,
cc6    =    1.394247,
ccc6   =    120.000,
dih6   =      0.000,
hc7    =    1.082198,
hcc7   =    120.000,
dih7   =    180.000,
hc8    =    1.082198,
hcc8   =    120.000,
dih8   =    180.000,
hc9    =    1.082198,
hcc9   =    120.000,
dih9   =    180.000,
hc10   =    1.082198,
hcc10  =    120.000,
dih10  =    180.000,
hc11   =    1.082198,
hcc11  =    120.000,
dih11  =    180.000,
hc12   =    1.082198,
hcc12  =    120.000,
dih12  =    180.000
basis,avtz
!gprint,orbitals,civectors
geomtype = zmat
geometry = {angstrom,
c;
c,   1, cc2;
c,   2, cc3,        1, ccc3;
c,   3, cc4,        2, ccc4,          1, dih4;
c,   4, cc5,        3, ccc5,          2, dih5;
c,   5, cc6,        4, ccc6,          3, dih6;
h,   3, hc7,        2, hcc7,          1, dih7;
h,   4, hc8,        3, hcc8,          2, dih8;
h,   5, hc9,        4, hcc9,          3, dih9;
h,   6, hc10,       5, hcc10,         4, dih10;
h,   1, hc11,       2, hcc11,         3, dih11;
h,   2, hc12,       3, hcc12,         4, dih12;
}
{hf,ENERGY=1.0E-10,orbital=1.0E-8;}
{df-hf,ENERGY=1.0E-10,orbital=1.0E-8;}
{df-mp2,ENERGY=1.0E-10,orbital=1.0E-8;}

2) In the frequency (numerical) calculation, it distort the molecule to get
Hessian. I want the forces at each displacement. When I check the output
files, it is not wring the information. How can I get the information?

I look forward to hear from you

Thank you
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