scf_for_excited_states
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scf_for_excited_states [2012/11/03 18:28] jelen |
scf_for_excited_states [2012/11/15 09:24] vlada |
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| ====== Constrained DFT for excited states ====== | ====== 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). | 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 ====== | ====== 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. | + | First, we show how to perform cDFT, i.e. SCF calculation of excited state, of formaldimine molecule CH2=NH. CH2=NH has in total 12 electron, from them 6 are double occupied molecular orbitals. Here we will run cDFT with a single excitation moving one electron from HOMO to LUMO state. The cDFT calculation is initiated by keywords icdft = 1. See example of fireball.in file. |
| Here is input file with initial geometry {{:scfe:CNH3.bas|}}. | Here is input file with initial geometry {{:scfe:CNH3.bas|}}. | ||
| + | {{:scfe:cnh3-w.png?400x200}} | ||
| + | |||
| fireball.in | fireball.in | ||
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| iquench = 0 | iquench = 0 | ||
| max_scf_iterations = 200 | max_scf_iterations = 200 | ||
| - | iscfe = 1 | + | icdft = 1 |
| &END | &END | ||
| Line 32: | Line 33: | ||
| </code> | </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 | + | To move electron from one orbital to another we need to create elh.inp input file in a directory. The first line means how many electrons is in the system. The first position of the second line means number of orbital where we want to create a hole. The second position determines occupancy of the hole (between 0-1). In this case there is missing one electron in 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> | <code> | ||
| 12 ! total number of electron | 12 ! total number of electron | ||
| Line 65: | Line 66: | ||
| </code> | </code> | ||
| - | ====== Example 3 ====== | + | {{:scfe:anim.gif}} |
| - | We can also calculate U function which is need to scissor operator calculations. | + | |
scf_for_excited_states.txt · Last modified: 2012/11/15 15:20 (external edit)
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