Hi,

This was added in the most recent revision (Rev D); perhaps you are using an earlier version of G09? [see http://gaussian.com/g_tech/rel_notes.pdf]

It also looks like the keyword for the functional is "B2PW91D3". I know that the original double hybrid B2PW91 functional was in earlier releases, and I think other empirical dispersion models as well.

Cheers

Thank you for your reply. Yes there are few inbuilt functional with D3 effect. I am particularly using "B3PW91". there are few research papers those used the same functional with D3. May be I must contact them.

you can see following input script for G09 Rev D.01 

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%chk=C:\Users\pramod\Desktop\cu-al2o3\test.chk

# opt b3pw91/6-31g geom=connectivity dft-d3=bj

Title Card Required

0 1

C 2.26027384 1.34703194 0.00000000

H 2.61692826 0.33822194 0.00000000

H 2.61694668 1.85143013 0.87365150

H 2.61694668 1.85143013 -0.87365150

H 1.19027384 1.34704513 0.00000000

1 2 1.0 3 1.0 4 1.0 5 1.0

2

3

4

5

Alexander Kaiser

http://wild.life.nctu.edu.tw/~jsyu/compchem/g09/g09ur/k_dft.htm#empdisp