Find answers or ask questions regarding Dalton calculations.
Please upload an output file showing the problem, if applicable.
(It is not necessary to upload input files, they can be found in the output file.)

linqiaosong
Posts: 2
Joined: 08 Feb 2020, 06:14
First name(s): Qiaosong
Last name(s): Lin
Affiliation: Wuhan University
Country: China

Last night, I calculated the phosphorescence response of the HF molecule using Dalton2019.alpha, and got the phosphorescence lifetime of the HF molecule. However, there is a question I wanna ask...The output information is following:

Code: Select all

`````` Phosphorescence transition rate from excited state no.  1
(Triplet->singlet transition, high-temperature limit)

Transition energy:  8.737 eV
or   141.915 nm

Length gauge:
Partial rates (H_SO): X-polarization 1.45786E+05 Transition moment :  1.434E-02
Length gauge:
Partial rates (H_SO): Y-polarization  0.0000     Transition moment :   0.00
Length gauge:
Partial rates (H_SO): Z-polarization  9494.0     Transition moment :  3.660E-03

Phosphorescence - length gauge:
Oscillator strength (/2PI)     (H_SO)    7.461901E-06
Dipole strength [a.u.]         (H_SO)    2.190450E-04
Dipole strength E-40 [esu**2 cm**2]      1.415134E+01
Total transition rate          (H_SO)    5.175992E+04 s-1
Total phosphorescence lifetime (H_SO)    1.931997E-05 s``````
As we all known, the lifetime of phosphorescence is following the formula: lifetime(s)=1.5/(Oscillator strength * (Transition energy(cm-1))^2)
If we use the result of output file, we will find that: lifetime=1.5/((7.461901E-06)*(2*PI)*(1/(141.915E-7)^2))=6.44345082456349E-06 s, which is the 1/3 of 1.931997E-05 s. What's more, we found that this phenomenon is common. Thus, I wanna know this factor 1/3 is the bug or the feature of Dalton Program?

The input and output files are following:
Attachments
test.out
test.mol
test.dal

olav
Posts: 145
Joined: 28 Aug 2013, 06:20
First name(s): Olav
Last name(s): Vahtras

### Re: A question about phosphorescence lifetime

Dear Qiaosong
For transitions between non-degenerate states, the general rule for the total transition rate is to average initial states and sum over final states. In the most common picture with a T->S transition, an ensemble average over the triplet states,assuming they are equally populated, shows up as a factor 1/3

Regards,
Olav

linqiaosong
Posts: 2
Joined: 08 Feb 2020, 06:14
First name(s): Qiaosong
Last name(s): Lin
Affiliation: Wuhan University
Country: China

### Re: A question about phosphorescence lifetime

Thank you very much for your answer

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