Do the coupling points need to be modified manually?

[YZhangSDU]

Dear Prof. Stephen Gibson,
You realy do a good job to write this program. I blieve that it has helped lots of people. I met one question when I used this program.
I wonder whether the cross point, namely the coupling point, need to be modified by myself, when I calculate the predissociation cross sections. Does this program automatically find the cross point?
This code depictedd in the program.
'about += f'Coupling at R = {self.R[240]:g} Angstroms (cm-2):'
Need I replace 'R[240]' with a new point which is at the vicinity of the cross point?
If the excited states potential energy curves are more than one and the cross points are at different internuclear distance R, Could this program accurately find the coupling points?

[stggh]

Hi Shuai Zhang,
Thanks for your query. Unfortunately, I am travelling until 5 November, and only have my mobile phone to access the code. Would you be able to list more lines of the code that demonstrate the issue. In generate the crossing point is unimportant to the coupled-channel code. However, if you are referring to the matching point mx for the problem of all closed channels, then that has importance. I will try to respond as best I can.

[YZhangSDU]

Dear Prof. Stephen Gibson, I am very pleased to hear from you and  I'm also sorry to disturb you while you are travelling, at the same time. I'll sort out my questions in more detail and I'll leave you a message after your travels. And now I hope you Enjoy your travels!   早 ***@***.***  

…

------------------ 原始邮件 ------------------ 发件人: "Steve ***@***.***>; 发送时间: 2022年10月18日(星期二) 下午4:34 收件人: ***@***.***>; 抄送: ***@***.***>; ***@***.***>; 主题: Re: [stggh/PyDiatomic] Do the coupling points need to be modified manually? (Issue #16) Hi Shuai Zhang, Thanks for your query. Unfortunately, I am travelling until 5 November, and only have my mobile phone to access the code. Would you be able to list more lines of the code that demonstrate the issue. In generate the crossing point is unimportant to the coupled-channel code. However, if you are referring to the matching point mx for the problem of all closed channels, then that has importance. I will try to respond as best I can. — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you authored the thread.Message ID: ***@***.***>

[stggh]

Hi Shuai Zhang,
I have returned from my travels.

Your query concerned the value for the couping at the potential curve crossing points, rather than an arbitrary R[240] internuclear distance.

The crossing point index, between two potential energy curves, i, j, may be simply determined from:

rx = np.argmin(np.abs(self.VT[i, i] - self.VT[j, j]))

I have modified cse.py to return the values of the coupling at the crossing points. NB these should (will!) match the inputted values. e.g.

(py310) [Gibbo:.+master/examples]$ ipython
Python 3.10.6 (main, Oct 24 2022, 16:07:47) [GCC 11.2.0]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.4.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: import cse

In [2]: B = cse.Cse('O2', dirpath='potentials', suffix='.dat',
   ...:             VT=['B3S-1', '3P1', 'E3S-1', '3PR1'],
   ...:             coup=[40, 4000, 0, 0, 7000, 0])

In [3]: B
Out[3]: 

Molecule: O2  mass: 1.32801e-26 kg, 7.99746 amu
Electronic states:   B³Σ₁⁻   ³Π₁   E³Σ₁⁻   ³Π₁
Coupling (cm⁻¹) at crossing point (Rx(Å)):
        B³Σ₁⁻      ³Π₁      E³Σ₁⁻      ³Π₁      
               40(1.455) 4000(1.185) 0(0.395)
                         0(1.225) 7000(1.220)
                                     0(1.330)

I will tidy up the formatting later. Note that the coupling values do match their inputted values.

I have also modified cse_setup.py to extract unicode electronic state labels from the inputted file name, so e.g. B3S-1.dat has the unicode term B³Σ_Ω ^-. These provide the labels for the tablulated couplings, provided by the Class __repr__.

I hope the above helps you define your problem.

[YZhangSDU]

Dear Prof. Stephen Gibson,
Thank you very much for your answer. Your further additions help me a lot and do address a question I had. Besides, I have some other questions. The more details and descriptions have been sent to your email address.
Looking forward to your reply!