scf_for_excited_states
Differences
This shows you the differences between two versions of the page.
| Both sides previous revision Previous revision Next revision | Previous revision | ||
|
scf_for_excited_states [2012/11/03 18:28] jelen |
scf_for_excited_states [2012/11/15 15:20] vlada |
||
|---|---|---|---|
| Line 1: | Line 1: | ||
| - | ====== Constrained DFT for excited states ====== | ||
| - | Constrained DFT allows to perform self consistent single electron excitation from arbitrary occupied orbital to unoccupied orbital (see example 1). There is also possibility to use quenching or geometry optimization of system in an excited state (see example 2). | ||
| - | Optionally, the cDFT might be used to estimate coulombic U parameter by removing or adding a single electron from arbitrary orbital (see example 3). | ||
| - | ====== Example 1 ====== | ||
| - | Let's try to calculate SCF of excited state of formaldimine molecule CH2=NH. CH2=NH has 12 electron, it means that there are 6 occupied molecular orbitals. We will move one electron from Homo to Lumo and run the SCFe. SCFe loop will be switched on by keywords iscfe = 1. See example of fireball.in file. | ||
| - | Here is input file with initial geometry {{:scfe:CNH3.bas|}}. | ||
| - | fireball.in | ||
| - | <code> | ||
| - | &OPTION | ||
| - | basisfile = CNH3.bas | ||
| - | icluster = 1 | ||
| - | nstepf = 1 | ||
| - | T_initial = 100.0 | ||
| - | T_final = 100.0 | ||
| - | sigmatol = 0.000000001 | ||
| - | dt = 0.01 | ||
| - | iquench = 0 | ||
| - | max_scf_iterations = 200 | ||
| - | iscfe = 1 | ||
| - | &END | ||
| - | &OUTPUT | ||
| - | iwrteigen = 1 | ||
| - | iwrtxyz = 1 | ||
| - | &END | ||
| - | &MESH | ||
| - | &END | ||
| - | |||
| - | </code> | ||
| - | |||
| - | To move electron from one orbital to another we need elh.inp input file. The first line means how much electrons is in the system. The first position in the secend line is number of orbital where we want to create hole. The second position means how "big" the hole is. In this case there is missing one electronin Homo orbital. The third line first position tells where is placed excited electron, the second position means how much electron you excite. Fig.1 | ||
| - | <code> | ||
| - | 12 ! total number of electron | ||
| - | 6 0.5 ! unocculied state | ||
| - | 7 0.5 ! occupied state | ||
| - | </code> | ||
| - | Results of such calculation is on the fig[1] | ||
| - | |||
| - | ====== Example 2 ====== | ||
| - | There is also possible to perform quenching of the excited state. The example is shown on the above mentioned system. CH2=N2 molecule can be found in two symetric conformations (Hydrogen bounded on N is in left or on the right side). Such transition is carried out by excitation of one electron from Homo to Lumo. Transition from one conformation to another pass through the conical intersection which is the local minimum of the excited state. In this example we will optimize geometry to the conical intersection. We only switch on keyword iquench = 1 and let them relax. Example of fireball in is below and elh.in file is the same as above: | ||
| - | <code> | ||
| - | &OPTION | ||
| - | basisfile = CNH3.bas | ||
| - | icluster = 1 | ||
| - | nstepf = 5000 | ||
| - | T_initial = 100.0 | ||
| - | T_final = 100.0 | ||
| - | sigmatol = 0.00000001 | ||
| - | dt = 0.5 | ||
| - | iquench = 1 | ||
| - | max_scf_iterations = 200 | ||
| - | iscfe = 1 | ||
| - | &END | ||
| - | |||
| - | &OUTPUT | ||
| - | iwrteigen = 1 | ||
| - | iwrtxyz = 1 | ||
| - | &END | ||
| - | |||
| - | &MESH | ||
| - | &END | ||
| - | </code> | ||
| - | |||
| - | ====== Example 3 ====== | ||
| - | We can also calculate U function which is need to scissor operator calculations. | ||
scf_for_excited_states.txt ยท Last modified: 2012/11/15 15:20 (external edit)
Page Tools
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Noncommercial-Share Alike 4.0 International
