# [molpro-user] Fwd: C8 disp coefficient

Yulia Kalugina amora at list.ru
Sun Jun 16 10:57:56 BST 2013

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Dear molpro community,

May be someone could help me with the obtaining of C8_000 dispesion coefficient from EOM-CCSD calculations?

Here is an example for N2-N2:

Uning proparator methof of Tatiana Corona we obtain <X;Y>:
a6633 := 136.6805842;
a4433 := 78.70125049;
a5533 := 78.70125049;
a5633 := -68.34029205;
a4633 := -68.34029205;
a4533 := -10.36095844;
a8833 := 97.21710728;
a8811 := 70.14620802;
a4411 := 57.06216406;
a5511 := 57.06216406;
a4511 := -7.578876794;
a6611 := 98.96657460;
a5611 := -49.48328727;
a4611 := -49.48328727;
as i understand, a6633=<zz,zz;zz> (for example).
here
1 - x
2 - y
3 - z
4 - xx
5 - yy
6 - zz
7 - xy
8 - xz
9 - yz
...

after, we have an expression for X integrals:
X2100=1/4(4*a6633+a4433+a5533-4*a5633-4*a4633+2*a4533)
X2101 ....

But when I use the formula for C8 isotropic coefficient, I have not obtained correct results (I obtain 4775 instead of correct value around 2500).
C000_8=X2100+2*X2101+2*X2110+4*X2111+2*X2120+4*X2121+X1200+2*X1201+2*X1210+4*X1211+2*X1202+4*X1212
(Ref. J Comput Chem 32: 279–290, 2011  :  "Long-Range Interaction for Dimers of Atmospheric Interest: Dispersion, Induction and Electrostatic Contributions for O2–O2, N2–N2 and O2–N2")

May be someone can indicate where is a mistake. For C6 coefficients I have no problems.

I would be very appreciated any help.

Best regards,

Yulia KALUGINA
LOMC - Université du Havre
25 Rue Philippe Lebon
BP 540 - 76 058 Le Havre cedex FRANCE
tel:  +33 (0)2 35 21 71 03
---------
OS - Tomsk State University
36, Lenina av. 634050 Tomsk RUSSIE
Mail : yulia.kalugina at univ-lehavre.fr , kalugina at phys.tsu.ru

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