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Thomas

thomaspijper@hotmail.com

Dear Matthieu, Alex,

To the best of my knowledge the TZV basis should be used with Cartesian d functions. So, it is not necessary to specify the D5 option (at least, as long as only s, p, and d functions are used).

Kind regards,

Thom

On Sat Dec 22 '12 9:30pm, Alex Granovsky wrote

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>Dear Matthieu,

>As to Mulliken and Lowdin population analyses, they do not work

>reliable for basis sets with lots of diffuse functions.

>In particular, the basis set you are using contains lots of (unneeded)

>diffuse functions and is quasi linearly dependent.

>This makes both Mulliken and Lowdin population analysis almost senseless.

>This also requires extra precision throughout all calculations

>to avoid some artifacts and numerical instabilities caused by these

>dependencies

>As to XMCQDPT2 properties and transition dipoles, you need to take

>into account that the computed values are the zero-order QDPT

>properties. This means that they include only a part of all effects

>due to interaction with the secondary space. Namely, they correctly

>include effects causing the rotation and intermixing of zero

>order states (i.e. CASCI vectors) within the model space but do

>not include the first order correction to wavefunction (i.e. the

>part of perturbed states which belongs to the secondary space).

>Thus these properties should be considered as the approximations

>to the "true" XMCQDPT2 properties.

>As to calculations with 10 and 20 states, it is easy to understand

>why you observed the picture you have reported.

>E.g. if you look at eigenvectors of the effecive hamiltonian for NSTATE=10 calculations, you'll see:

>

EIGENVECTORS OF THE EFFECTIVE HAMILTONIAN 1 2 3 4 5 -286.840923-286.681744-286.644400-286.613064-286.607064 1 -0.992457 0.000006 0.048901 -0.000006 0.011915 2 0.000003 0.925328 -0.000055 -0.367836 -0.000087 3 0.049198 0.000078 0.943674 0.000100 -0.163528 4 0.000007 -0.228667 0.000129 -0.657996 -0.000181 5 0.015554 0.000044 0.215843 0.000090 -0.041182 6 0.030684 -0.000013 0.168242 -0.000288 0.980470 7 0.000000 0.253590 0.000003 0.631977 0.000230 8 0.000009 -0.164838 -0.000112 -0.179840 -0.000024 9 -0.015825 -0.000113 0.176117 -0.000128 -0.031814 10 0.105713 -0.000006 -0.034310 0.000015 -0.095325

>that S1 state obtained at CASSCF level at PT2 level strongly

>interacts with S3, S6, and S7 states. Similarly, the zero-order

>S2 state is intermixed with S4, S5, and S8 states. These are

>the effect you cannot capture in NSTATE=3 computations. You really

>need to perform calculations with extended effective Hamiltonians

>to capture these important effects.

>A few additional comments. With Firefly version you are using,

>the weights of states in constructing averaged density matrices

>will be equal for all nstate=10 or 20 states (as indicated in the

>output):

>

*** WEIGHTS OF STATES IN COMPUTING AVERAGED DENSITY MATRIX (AVECOE) ----------------------------------------------------------------------- 1 2 3 4 5 1 1.000000D+00 1.000000D+00 1.000000D+00 1.000000D+00 1.000000D+00 ----------------------------------------------------------------------- 6 7 8 9 10 1 1.000000D+00 1.000000D+00 1.000000D+00 1.000000D+00 1.000000D+00 --------------------------------------------------------------------- --This is most likely not exactly the calculations you want to perform. You thus need to either set all other elements of avecoe and wstate arrays of $xmcqdpt2 group to zero explicitly, or to use the following syntax:wstate(1)=1,1,1,-0 avecoe(1)=1,1,1,-0>Next, the irot=1 settings correspond to the XMCQDPT2' variant

>of theory as designated in my paper on XMCQDPT. Do you have some

>good reasons to use this approximation to the exact theory? If not,

>I'd recommend leave this option intact.>Finally, you may need to use D5 option with the basis set you have

>selected (it is most likely usually used as spherical basis set,

>I do not remember exactly at moment).>I'm attaching the corrected input file for your reference.

>Hope this helps.

>Kind regards,

>Alex Granovsky

>

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>

>On Wed Dec 19 '12 4:45pm, Matthieu Sala wrote

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

>>Dear Firefly users,>>I am studying the photochemistry of the aniline molecule (Ph-NH2) using the XMCQDPT2 method, and I have trouble to obtain accurate values for the oscillator strengths, partial charges and dipole moments in the two first pipi* excited states.

>>In a previous CASSCF study, the first pipi* state has been assigned as a local excitation while the second as a charge transfer state with ca. 0.2 electron transfered from the N atom to the C atom at the opposite part of the ring.

>>Moreover, accurate values (in comparison with experiments) for the oscillator strength has been reported at the SAC-CI, TD-CAMB3LYP and EOM-CCSD levels of theory. Experimental values are 0.028 for the 1pipi* and 0.144 for the 2pipi* states.>>I use a minimal active space of 8 el in 7 orb (3pi, 3pi* and the N lone pair) to describe excited pipi* states. I use a SA3-CASSCF reference wavefunction.

>>Then I performed XMCQDPT2 calculations with increasing size of the model space (3, 10 and 20).>>I have several problems. First Mulliken and Lowdin charge analysis give very different results (I think the Lowdin is more reasonnable).

>>Second the dipoles, oscillator strength and partial charges change a lot when the model space size is increased. For NSTATE=3 in XMCQDPT2, the results are quite close from what we can expect (although the oscillator strength for the 1pipi* state is significantly underestimated).

>>But when NSTATE is increased, the results change a lot. The oscillator strengths are greatly overestimated and the first pipi* state seems to acquire a charge transfer character.>>Could someone tell me what am I doing wrong ?

>>Any help would be greatly appreciated.>>I attach the inputs and output of the XMCQDPT2 calculations

>>(all merged in one text file).>>Best regards.

>>Matthieu Sala

*[ This message was edited on Sat Dec 22 '12 at 11:07pm by the author ]*

Sat Dec 22 '12 11:07pm

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