2.6.7. import{} (optional)

Specifications for importing data from a file or generating them from an analytic function, e.g. electrostatic potential, alloy profile, strain profile, doping profile, generation rate profile, electron or hole Fermi level profile.

Once a file has been imported or a function has been defined, it can be used several times, e.g. the same file could include the alloy concentration of a ternary for different region objects.

Data with dimensionality deviating from the simulation dimension can also be imported, e.g. an absorption spectrum for solar cell modeling.

directory (optional)
value:

string

example:

“D:\import_files\”

Name of directory where files to be imported are located (if data are imported from files)

file{} (optional)
name

Name for referencing the imported data in the input file, e.g. “imported_potential_profile_2D”

example:

“1D_import”

filename

Name of file which is imported. Two ways of using are available.

One can define an absolute path to a file, e.g., "D:\\precious_data.dat". If so then import{ directory } is ignored if specified.

example:

“D:\any_filename.dat”

If the path is not specified here, e.g., "precious_data.dat" then the file must be located in the directory specified by import{ directory }.

example:

“any_filename.dat”

format

Format of the file to be imported. Formats .fld and .dat are supported for options AVS and DAT, respectively.

options:

AVS DAT

scale (optional)

A factor used to multiply the imported data. Can be used to change units of imported data for consistency with nextnano++, e.g., conversion from J to eV.

examples:

1.6022e-19 -1

default:

1

number_of_dimensions (optional)

Explicit specification of the number of dimensions. Can be only used for .dat files.

options:

1 2 3

default:

dimensionality of the simulation (see global{})

analytic_function{} (optional)

define analytic functions to be imported here. Does not need to be defined if data are imported from files.

name

Name for referencing the imported function in the input file, e.g. “analytic_function_gaussian”

example:

“Analytic_Potential”

function (optional)

String defining the function in case only one component needs to be defined, otherwise use component.

example:

“1+2*x^2+exp(y)”

Attention

One should use the syntax allowed for functions:

  • white spaces are ignored

  • valid operators are “+”, “-”, “*”, “/” and “^”

  • multiplication signs always have to be spelled out (i.e. “5*x” is valid, “5x” is not)

  • variable names are fixed to “x”, “y” and “z” (capital letters are also allowed)

  • additional functions also available (e.g. “exp” , “sqrt”, “sin”, see full list below), have to be followed by brackets (“exp(x)” is valid, “exp x” is not)

  • global variables are allowed if preceded by “$” (e.g. “$PI”)

  • exponential notation (“2e-3” or “4E10”) is allowed

See also table at the bottom of this site.

label (optional)

Label to be displayed in legend in case only one component is defined, otherwise see component.

example:

“potential_label”

component{} (optional)

In case multiple components are needed, define one component group for each component.

function_i

String defining the function for this component.

example:

“1D_import”

label (optional)

Label to be displayed in legend for this component.

example:

“component_label”

output_imports{} (optional)

Output all imported data including scale factor. The filenames correspond to the entry given in name = .... The files will be written to a folder called Imports/.

Operators and Functions supported by analytic_function{} group, sorted with decreasing precedence:

Operators

power (exponentiation)

^

multiplication, division

* /

plus and minus

+ -

round arithmetic brackets

( )

Functions

sqrt()

square root \(\sqrt{\text{ }}\)

cbrt()

cubic root \(\sqrt[3]{\text{ }}\)

exp()

exponential function \(\exp({\text{ }})\)

log()

natural logarithm \(\log\)

ln()

natural logarithm \(\ln\)

log2()

decadic logarithm (base 2) \(\log_{2}\)

log10()

decadic logarithm (base 10) \(\log_{10}\)

sin()

sine \(\sin({\text{ }})\)

cos()

cosine \(\cos({\text{ }})\)

tan()

tangent \(\tan({\text{ }})\)

asin()

acrsine \(\sin^{-1}({\text{ }})\)

acos()

arccosine \(\cos^{-1}({\text{ }})\)

atan()

arctangent \(\tan^{-1}({\text{ }})\)

sinh()

hyperbolic sine \(\sinh({\text{ }})\)

cosh()

hyperbolic cosine \(\cosh({\text{ }})\)

tanh()

hyperbolic tangent \(\tanh({\text{ }})\)

asinh()

inverse hyperbolic sine \(\sinh^{-1}({\text{ }})\)

acosh()

inverse hyperbolic cosine \(\cosh^{-1}({\text{ }})\)

atanh()

inverse hyperbolic tangent \(\tanh^{-1}({\text{ }})\)

erf()

error function \(\text{erf}({\text{ }})\)

erfc()

complementary error function \(\text{erfc}({\text{ }})\)

gamma()

Gamma function \(\Gamma({\text{ }})\)

fdm3half()

complete Fermi–Dirac integral \(F_{-3/2}({ })\) of order -3/2 (includes the \(1/\Gamma(-1/2)\) prefactor)

fdmhalf()

complete Fermi–Dirac integral \(F_{-1/2}({ })\) of order -1/2 (includes the \(1/\Gamma(1/2)\) prefactor)

fdzero()

complete Fermi–Dirac integral \(F_{0}({ })\) of order 0 (includes the \(1/\Gamma(1)=1\) prefactor)

fdphalf()

complete Fermi–Dirac integral \(F_{1/2}({ })\) of order 1/2 (includes the \(1/\Gamma(3/2)\) prefactor)

fdp3half()

complete Fermi–Dirac integral \(F_{3/2}({ })\) of order 3/2 (includes the \(1/\Gamma(5/2)\) prefactor)

abs()

absolute value \(|{\text{ }}|\)

floor()

floor function floor(x): largest integer \(\le x\)

ceil()

ceiling function ceil(x): smallest integer \(\ge x\)

round()

rounds the number to the nearest integer

sign()

sign function

heaviside()

Heaviside step function (corresponds to isnotnegative())

ispositive()

check if value is positive

isnegative()

check if value is negative

iszero()

check if value is zero

isnotpositive()

check if value is not positive

isnotnegative()

check if value is not negative (corresponds to heaviside())

isnotzero()

check if value is not zero