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David Shobe

avidshobe@yahoo.com

Related question:

When you get the following error message

THE INPUT BASIS SET CONTAINS A LINEAR DEPENDENCE

it doesn't tell you which functions are redundant, unlike the case for a near linear dependence. How do you know which functions to delete?

Thanks for you help so far,

--David

On Wed Apr 6 '16 10:07pm, Alex Granovsky wrote

----------------------------------------------

>Dear David,

>Dear Pedro,

>Search this site on "mp4(d)" returns these two useful threads:

>

>

>http://classic.chem.msu.su/cgi-bin/ceilidh.exe/gran/gamess/forum/?C393fb1c3f2vS-7378-1007-00.htmhttp://classic.chem.msu.su/cgi-bin/ceilidh.exe/gran/gamess/forum/?C393fb1c3f2vS-7378-1007-00.htm

>http://classic.chem.msu.su/cgi-bin/ceilidh.exe/gran/gamess/forum/?C3d2d5e75bcsK-8577-846+00.htmhttp://classic.chem.msu.su/cgi-bin/ceilidh.exe/gran/gamess/forum/?C3d2d5e75bcsK-8577-846+00.htm

>

>

>In brief, this job has almost linearly dependent basis set. As printed

>in the output file:

>

>

>

THE OVERLAP MATRIX HAS 4 EIGENVALUES BELOW 1.1E-04 THE SMALLEST OF THESE IS 1.35832E-09.

>The eigenvalue of overlap matrix of 1.35832E-09 corresponds

>to a severe quasi-linear dependence.

>The sensitivity of MP4(D) term of the MP4 energy to the linear

>dependence in the AO basis set has been already discussed on this

>forum several times. The MP4(D) term is the most sensitive one

>because during its computation one needs to transform integrals and

>other quantities from AO to MO basis, then back from MO to AO,

>and finally from AO to MO again. Each transformation kills up to

>several significant digits of the result (more precisely,

>the number of digits lost is directly related to the condition

>number of the overlap matrix) if all orbitals (including virtual

>ones) are not computed very precisely. So in the worst case like

>this one, one can lost all significant digits.

>

>

>What to do?

>One need to delete some orbitals to increase the smallest

>eigenvalue of the overlap matrix.

>As output indicates, the most problematic orbital is:

>

0.2857E-08 - C 5 S, SHELL 31, AO 73

>i.e. the S part of the diffuse L shell on the atom C5

>I attached archive with modified input file as well as

>the corresponding output file. In the new input, the

>problematic orbital was removed by replacing L shell

>located on atom C5 by P shell. Otherwise, the $DATA

>group of the modified input is equivalent to the initial

>$DATA and $BASIS groups.

>I also increased ICUT and ITOL, and disabled fdiff.

>Finally, I tightened nconv to 6 as recommended in

>output.

>The smallest eigenvalue of overlap matrix is now:

>

THE SMALLEST OF THESE IS 4.10644E-08.

>i.e. ca. 30 times better!

>

>

>As a result, we obtain:

>

RESULTS OF MOLLER-PLESSET 4TH ORDER CORRECTION ARE E(RHF) = -191.5685568750 E(D,2) = -0.6457464825 E(MP2) = -192.2143033575 E(D,3) = -0.0166674371 E(D,2+3) = -0.6624139197 E(MP3) = -192.2309707947 E(S,4) = -0.0073886039 E(D,4) = -0.0200238070 E(D,2+3+4) = -0.6824377267 E(T,4) = -0.0337953970 E(R+Q,4) = 0.0168396781 E(SDTQ,4) = -0.0443681298 E(SDTQ,2+3+4)= -0.7067820495 E(MP4-SDTQ) = -192.2753389245

>Hope this helps.

>Kind regards,

>Alex Granovsky

>

>

>

>

>

>

>

>

>On Mon Apr 4 '16 0:12am, David Shobe wrote

>------------------------------------------

>>Is this the correct MP4 energy for this molecule (1,3-pentadiyne)?

>> RESULTS OF MOLLER-PLESSET 4TH ORDER CORRECTION ARE

>> E(RHF) = -191.5694925024

>> E(D,2) = -0.6494633272

>> E(MP2) = -192.2189558295

>> E(D,3) = 0.2696414733

>> E(D,2+3) = -0.3798218539

>> E(MP3) = -191.9493143563

>> E(S,4) = -0.0517477560

>> E(D,4) = -26.2790188653

>> E(D,2+3+4) = -26.6588407192

>> E(T,4) = -0.0344433158

>> E(R+Q,4) = 0.0171693598

>> E(SDTQ,4) = -26.3480405772

>> E(SDTQ,2+3+4)= -26.7278624311

>> E(MP4-SDTQ) = -218.2973549335

>>

Sat Apr 9 '16 8:37am

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