| 10:29:21 AM PST - Sat, Feb 4th 2017 |
|
I am interested in RT-TDDFT. I will use this method to calculate the UV-spectrum of a (huge) sensitizer molecule (about 100 atoms roughly). I guess that the calculation will heavily consume the computing time. That's why I need to know the possible maximum time step I can use. However, I am just curious about conversion of Unit for total time & time step and having two following questions.
Quantity Conversion
Time 1 au = 0.02419 fs
Length 1 au = 0.5292 A
Energy 1 au = 27.2114 eV
Electric field 1 au = 514.2 V/nm
Dipole moment 1 au = 2.542 D
Reference
The studied spectral bandwidth is 300 - 700 nm. Then I convert this range from nm to fs using a converter on this website click here., which gave me a resulting between 1.00 - 2.33 fs.
I selected 1.00 fs (300 nm), which has a highest energy in ev, as a ωmax
So, why is this time step value (in atomic unit) so large ?
And also if I want to calc spectrum to cover UV range, how much total time I should use ?
Thank you in advance for your kind comment and valuable answer.
Best,
Rangsiman
|
|
|