Options for Coulomb diffusion, gravitational field, and electromagnetic field
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.. list-table:: **nspred**
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   * - Value
     - Explanation
   * -  | (D=0)
     -  | Options for Coulomb diffusion (angle straggling) [#]_ .  Note that this option is not applicable for electrons and positrons.
   * -  | =0
     -  | Without Coulomb diffusion.
   * -  | =1
     -  | With Coulomb diffusion by the original NMTC model.
   * -  | =2
     -  | (Recommended) With Coulomb diffusion by the Lynch's formula based on the Moliere  theory [#]_ .
        | You can also set nspred=-1, -2.  When it is specified as a negative value, Coulomb scattering is always  taken into account; when specified as a positive value, Coulomb  scattering is taken into account until a source particle occurs the  first reaction.  To reduce calculation time, setting 0 or positive values is recommended  for usual calculations.  For transport calculations of charged particles in a large scale with  very low density or highly transparent charged particles such as muons,  please set the negative values.
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.. list-table:: **ascat1**
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   * - Value
     - Explanation
   * -  | (D=13.6)
     -  | Parameter  :math:`A`  in the Lynch's formula (see below) for nspred=2.
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.. list-table:: **ascat2**
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   * - Value
     - Explanation
   * -  | (D=0.038)
     -  | Parameter  :math:`B`  in the Lynch's formula (see below) for nspred=2.
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.. list-table:: **nedisp**
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   * - Value
     - Explanation
   * -  | (D=0)
     -  | Energy straggling option for charged particle and nuclei.  Note that this option is not applicable for electrons and positrons.
   * -  | =0
     -  | Without energy straggling.
   * -  | =1
     -  | (Recommended) With Landau Vavilov energy straggling [#]_ .

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.. list-table:: **gravx**
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  * - Value
    - Explanation
    -  | (D=0)
    -  | x-component of gravity direction.

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.. list-table:: **gravy**
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  * - Value
    - Explanation
    -  | (D=0)
    -  | y-component of gravity direction.

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.. list-table:: **gravz**
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  * - Value
    - Explanation
    -  | (D=0)
    -  | z-component of gravity direction.



gravx, gravy, gravz represent the directions of gravity; the  gravitational force is effective for neutrons at energies below 1 eV.
For example, if gravx=1, gravy=0, gravz=0, the direction of the  gravitational force is negative along the x-axis. 
imagnf is a parameter equivalent to ielctf which enables both [magnetif field] and [electro magnetic field]. From Ver.3.36, imagnf and [magnetif field] are deprecated because they were merged to ielctf and [electro magnetic field], respectively. 

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.. list-table:: **usrmgt**
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  * - Value
    - Explanation
  * -  | (D=1)
    -  | Options for user subroutine of time dependent magnetic field defined in [electro magnetic field].
  * -  | = 1
    -  | usrmgt1.f, which includes Wobbler magnet, is used.
  * -  | = 2
    -  | usrmgt2.f, which includes Pulse magnet, is used.

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.. list-table:: **usrelst**
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  * - Value
    - Explanation
  * -  | (D=1)
    -  | Options for [elastic option].
  * -  | = 1
    -  | usrelst1.f, for Bragg scattering, is used.
  * -  | = 2
    -  | usrelst2.f, a sample program, is used.

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.. list-table:: **ielctf**
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  * - Value
    - Explanation
  * -  | (D=0)
    -  | Options for electromagnetic field.
  * -  | = 0
    -  | Without electromagnetic field.
  * -  | = 1
    -  | With electromagnetic field. If you want to precisely calculate the trajectory of charged particles (except electrons and positrons) under a strong electromagnetic field that significantly bends their trajectories within a short distance (less than a few cm), set the maximum flight mesh size ( **deltg** ) in the electromagnetic field to a smaller value.




.. [#]  When describing a scattering process on thin films less than 1cm,  delt0 should be set to 1/10 of its thickness.  
.. [#]   :math:`\sigma=A\frac{\sqrt{X/X_0}}{p\beta}[1+\frac{B}{\log_{10}(e)}\log_{10}(X/X_0)]` : Eq.(12) in  G.R. Lynch and O.I. Dahl, Nucl. Instrum. Methods Phys. Res, B 58, 6-10 (1991). 
.. [#]  About these models, see the web site: "http://www.dnp.fmph.uniba.sk/cernlib/asdoc/geantold/H2GEANTPHYS332.html"