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  1. H

    Source of light

    Hello, If we consider a source of light (in a point x), is it wright to say that the intensity decreases in 1/r2 ? Thank you !
  2. H

    DFT vs. HF (time argument)

    Hi everyone, How hybrid functional can be quicker than HF ? Because we have to use the HF exchange part, so we have to solve the problem with HF before, am I right ? Thank you
  3. H

    Basis set QM

    Hello ! When we say that we use a 6-31G for a molecule (ex: N2), it is this number of gaussian (6+3+1) for both of the atoms or for each atom ? Thank you
  4. H

    Type of laser -- which is easiest to make?

    Hello, Which type of laser are easier to make ? Micro-wave (MASER), infrared, visible light, UV... ? Which type of light leads in an easier way to a population inversion ? Is it maser because the level energy involved are closed ? Thank you
  5. H

    Stuttgart ECP

    Hello ! I don't really undestand the difference between these two terms. Stuttgart Librairy is a pseudopotential, right ? What is SDD? (I've seen that this is a EDP too is that ok?) So what does that mean if we say that we take a Stuttgar t effective core SDD basis set ? What is the difference...
  6. H

    DFT exchange energies

    Hello ! How does the inclusion of a fraction of the HF "exact exchange energies" in an hybrid functional (B3LYP for example) can degrade the quality of the results ? I mean that the results are worst than expected because of the HF exchange, but if we call it "exact" how is it possible ? Thank...
  7. H

    Laser effect

    Hello, Can we make a laser with any type of radiance (IR,UV,visible,microwave,..) ? If we consider a three level system for example. In such a system, how can we avoid absorption from level 1 to level 2 ? Is it by choosing atoms/molecules in which the level 2 is greater than the fundamental ...
  8. H

    HF / DFT

    I've read an article about computational chemistry in which the authors were performing a geometry optimization. For this purpose, they firstly optimized the geometry at HF/6-311++G(d,p) level with full relaxation on the potentiel energy surface (what does that mean exactly ? Can we extract this...