PFChrom v5 Documentation Contents AIST Software Home AIST Software Support

ZDD - [T] Generalized Student's t (Asymmetric)

This is the Zero
Distortion Density (ZDD) used in the GenHVL[T] models. The [T] model is a further generalization of
the [S] ZDD. The a_{3} parameter (as in the [S] model) adjusts the nu or DOF of the Student's
t, altering the fourth moment or kurtosis of the peak. The a_{4}
parameter in the ZDD nomenclature below adjusts the asymmetry, and thus the third moment or skew of the
peak.

This is also the ZDD used in the GenNLC[T] models. For the GenNLC[T]
models, a_{0}, a_{1},
and a_{3} will be identical. The a_{2}
width or second moment term will reflect a kinetic time constant, and a_{4}
will reflect an NLC asymmetry normalized to 0.5 for the Giddings ZDD. Please see the GenHVL
and GenNLC equivalence topic for further details.

[T] ZDD

a_{0} = Area

a_{1} = Center

a_{2} = Width

a_{3}= DOF or nu (1>a_{3}>1000000,
Gaussian nu=Infinity, Lorentzian nu=1)

a_{4} = Asymmetry (
fronted -1 > a_{4}
> 1 tailed)

Built-In Peak Model

GenStudent (Statistical family)

User-Defined Peaks and View Functions

GenStudent(x,area,center,width,s-nu,z-asym) Generalized
Student's t Area

GenStudent_C(x,amplitude,center,width,s-nu) Gen.
Student's t cumulative

GenStudent_CR(x,amplitude,center,width,s-nu) Gen.
Student's t reverse cumulative