5 thoughts on “Lumen code is online!

  1. WENSHEN SONG

    Hello,
    I try to do SHG calculation in lumen, but I cannot find a forum for lumen so I ask questions here. I wonder how to set the direction for the SHG tensor chi. As far as I am concerned, Chi_ijk could be expressed as P_i=Chi_ijk E_j E_k, so how can we determine the i,j and k in lumen? I read the tutorial for lumen SHG in AlAs, and the external field is set as
    ExtF_Dir
    1.000000 | 1.000000 | 0.000000 |

    Does it mean setting j=x and k=y? And the output for x,y,z directions should give Chi_xxy, Chi_yxy, Chi_zxy? If so, why does the tutorial plot give a label as Chi_xyz?

    Reply
    1. attacc Post author

      Dear Wenshen

      thank you for interesting in Lumen.
      I will add a Forum to Lumen soon 🙂
      >
      > I wonder how to set the direction for the SHG tensor chi. As far as I am concerned, Chi_ijk could be expressed as P_i=Chi_ijk E_j E_k. So, how can we determine the i,j and k in lumen? I read the tutorial for lumen SHG in AlAs, and the external field is set as
      > ExtF_Dir
      > 1.000000 | 1.000000 | 0.000000 |

      in this example there is only one field, therefore E_j=E_k.

      > Does it mean setting j=x and k=y?
      Yes the three numbers in the input are the x,y z direction, I modified the tutorial to make it clear

      > And the output for x,y,z directions should give Chi_xxy, Chi_yxy, Chi_zxy? If so, why does the tutorial plot give a label as Chi_xyz, for which should actually be Chi_zxy?
      In this example we calculate Chi_zxy but in AlAs Chi_zyx=Chi_xyz=Chi_yxz
      see also Eq. 24 in https://journals.aps.org/prb/abstract/10.1103/PhysRevB.82.235201
      I modified the tutorial to make this point clearer this point and corrected the figure

      Yours
      Claudio

      Reply
  2. Espirid

    Hi.
    I made a new post in the Lumen forum, however I have not received any response, I apologize if my attempt to find an answer here is too much.

    I have tried to make a calculation of SHG, however I have reached a limit with the following error.
    .
    .
    [ERROR] STOP signal received while in: [04.01] Initialization
    [ERROR] Spin-polarized systems not fully implemented

    Unfortunately I can not ignore the polarization of the spin, so I would like to know if someone has a hint or a way to solve such a situation.

    Greetings and thanks for your time.

    Reply
    1. attacc Post author

      Dear Espirid

      unfortunatelly the spin-polarization at present the spin-polarization is not implemented in Lumen.
      It should not be difficult to generalize it to the spin-polarized case, but I have no
      time to work on it, at least this month.
      You can try to have a look, and I can help you, or we can discuss in April of possible implementations.

      Best
      Claudio Attaccalite

      Reply
      1. Espirid

        Thank you very much for your prompt response.
        Unfortunately my knowledge in programming is not very good, even so I think I will try to check and see if I am lucky with the implementation.
        Could you tell me where to attack code?

        Thank you very much for your time to appreciate it.

        regards

        Reply

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