Tian

]]>There are some reasons why I didn't implement NBO into Multiwfn:

1 The NBO program written by weinhold et al. is already very nice, fast and easy-to-use. Most important analyses in the NBO framework can be realized in the freely available NBO 3.0/3.1. Although the later versions of NBO are no longer free-of-charge, the price is inexpensive (100 USD).

2 NBO consists of a bunch of analysis methods, many technique details are not published, therefore some methods are uneasy to be implemented, and even if they are supported by Multiwfn, the results may be clearly different to NBO program.

3 Lots of things that NBO can do in fact can also be done by Multiwfn via different ways (sometimes better ways). For example, NBO orbital analysis can be largely replaced by localized molecular orbital analysis in Multiwfn, the NBCP analysis can be essentially equivalently realized by Multiwfn in topology analysis module (In Multiwfn, properties at CPs can be decomposed to contribution of orbitals, including NLMOs).

The most valuable and irreplaceable component of NBO framework I think is generation of natural atomic orbital, the NAOs are also utilized by some functions of Multiwfn, such as decomposition of Wiberg bond order to atomic orbital pair contributions. Due to its absolute importance, generating NAO is the only component in NBO framework that I intend to add to Multiwfn in future versions.

Best wishes,

Tian Lu

]]>that did the trick! Thank you very much.

Best wishes,

Michael

In Multiwfn, Fukui function can be characterized in many different ways:

(1) Fukui function can be plotted as isosurface map, see Section 4.5.4 of Multiwfn manual for example, this is the most commonly used way of analyzing Fukui function

(2) Fukui function can also be studied in terms of "condensed Fukui function", which is a quantitative indicator of total amount of Fukui function on each atom site, please check Section 4.7.3 of the manual for example.

(3) The "quantitative molecular surface analysis " module of Multiwfn can map Fukui function on molecular surface to investigate its distribution character (e.g. average value) on local molecular surface corresponding to various atoms, this method is not popular currently but undoubtedly useful, see Section 4.12.4 of the manual for example.

These kinds of analyses can also be applied to dual descriptor.

]]>Dear Sobereva.

As it was stated in the manual "the .wfn file generated by ORCA are usually non-standard and cannot be properly recognized by Multiwfn. Therefore, using .molden file as input file of Multiwfn instead is highly recommended, see below", however, the *.molden file cannot be properly recognized by Multiwfn. Upon analyzing, it yields no information from this file. Alternatively, using Gaussian-made *.wfn, Multiwfn gives proper analysis.

So, could you resolve the problem with Orca-made *.wfn?

Hi,

Please first ensure that you are using the latest version of both ORCA and Multiwfn. At least, Multiwfn 3.5(dev) is completely compatible with the .molden file produced by ORCA 4.0.1.2.

I am not sure why "*.molden file cannot be properly recognized by Multiwfn". It is better to upload the compressed input file so that I can better figure out the reason. (If the file is larger than 5MB after compression, please send the file to my E-mail sobereva[at]sina.com).

For the latest version of Multiwfn, if the suffix of the molden input file is .molden or .molden.input, then the file will be recognized as molden input file and the wavefunction information will be loaded from it, and you can find brief description about present wavefunction on screen after loading finished. If the suffix is not recognized by Multiwfn, then no information will be loaded from the file and thus no analysis result will be finally yielded.

Also note that current version of Multiwfn is also compatible with the .wfn file generated by ORCA 4.0.x.

Best wishes,

Tian

]]>Best regards]]>

Dear lijingbai2009,

The reason of introducing the factor of -1 is that the convention used by ORCA is very weird. For F(+3), F(-3) and G(+3) G(-3) G(+4) G(-4), the basis functions are normalized to -1 rather than 1, therefore in order to make analysis result meaningful, the corresponding LCAO coefficient must be multiplied by -1. I don't know why ORCA uses such strange convention.

Best wishes,

Tian

Dear Tian Lu,

That's the exact reason I wanted to know. ORCA does have many tricks inside. Now everything are clear for me. Thanks a lot again.

Best regards,

Jingbai

Hello everybody,

I have performed TD-DFT calculations on an organic molecule using

G09(D.01), and analysed the excitations by means of the Natural

Transition Orbital scheme.

In most cases the situation is pretty clear cut, and the NTOs provide a

straigthforward way to "visualise" the transitions. However, I am

confused by a result for one state, in which the CI coefficients for two

contributing transitions are -0.45 (HOMO-2 -> LUMO) and 0.51 (HOMO ->

LUMO+2). To me this suggests that these MO pairs have almost equal weight

in the expansion, which should be reflected in the NTOs. However, the

particle NTO very much resembles the canonical HOMO. Would this be

expected? I would have thought that the NTO should look different in this

case, but perhaps I am wrong here. I wouldn't assume that these are

simply a sum of the two, since they are obtained by a SVD procedure.

To generate these I pretty much follow a standard protocol, reading the

.chk file from the TD job into a new calculation with this route section

# Geom=AllCheck ChkBas Guess=(Read,Only) Density=(Check,Transition=n)

Pop=(NTO,SaveNTO)

Then I use formcheck and cubegen to generate the plot for the respective

transition "n" (so, individual jobs for each transition are run).

In this context I also wondered how to obtain the associated weight

(sigma) of a NTO pair. I have seen these in some publications, presented

along with the excitation energy and oscillator strength.

Thanks for you help

My reply

Dear Tobias Kraemer,

Please do not forget to check eigenvalues of NTO pairs, they reflects contribution of each NTO pair to the electronic excitation. Although NTO analysis works well for most cases, namely only one dominating NTO pair could be found; however, NTO analysis is not always useful, because there are also many cases the NTO pair with largest eigenvalue doesn't contribute to nearly 100% (or >85%) of electronic excitation, and thus you still have to simultaneously inspecting more than one pair of orbitals to fully understand the character of the excitation.

If you suspect if the NTO analysis result you obtained is completely correct, you can also use Multiwfn program to carry out NTO analysis and compare the result (for Gaussian user, .fch file and Gaussian output file are needed as input file, see Section 4.18.4 of the Multiwfn manual for example, you will find the use is rather easy). The additional advantage of using Multiwfn to perform NTO analysis is that the resulting NTOs can be directly visualized and analyzed (i.e. calculating orbital composition, evaluating position of orbital centroid, etc.) in the code, and when you want to respectively analyze NTO for many states, you do not need to repeat Gaussian calculation multiple times (Gaussian is only needed to run once, and then using the resulting files, in Multiwfn you can directly select the state to generate NTO).

By the way, when NTO analysis is not as useful as expected due to aforementioned reason, you can consider to use the hole-electron analysis in Multiwfn instead, see Section 3.21.1 of the manual for introduction and Section 4.18.1 for example. In any case, this analysis represents the excitation as transition from "hole" to "electron", therefore by simply visualizing hole distribution and electron distribution (they can be drawn as isosurfaces in the same map in Multiwfn), you will be able to fully capture the character of the electronic excitation.

Best wishes,

Tian Lu

For example, you want to calculate cube file of MO(26)^2-MO(25)^2, boot up Multiwfn and input below commands

test.molden

200

3 // Export cube file containing orbital wavefunction

25,26 // The two orbitals needed later

2 // Medium quality grid

1 // Export grid data

Now you have orb000025.cub and orb000026.cub in current folder.Reboot Multiwfn and input

orb000026.cub

13 // Process Grid data

11 // Grid data calculation

11 // A^2-B^2=C operation

orb000025.cub

Now, the grid data in memory corresponds to MO(26)^2-MO(25)^2, you can then use option -2 to visualize it, or use option 0 to export it as .cub file.

Any kind of valence electron density analysis can be easily done via Multiwfn, including plotting it as map, topology analysis, basin analysis and so on. The way of plotting valence electron density map is mentioned in Section 4.6.2 of Multiwfn manual.

Hoping that valence electron density analysis will be become a popular tool for studying electronic structure problems!

]]>Dear Dr. Lu

What does it mean to excitation binding energy?

wawa

It should be exciton binding energy

]]>Indeed there is no much difference between density and electrons per grid point for uniform cubic and rectangular grids.

I was a bit confused, because for more "complicated" radial+angular grid the weight for each point is not just dx*dy*dz.

One gets large density contribution close to nuclei, which vanishes once it is multiplied by weights.