Statistical Thermodynamics

With Mathcad

Starting the program - Click on:

"Arbeitsplatz"->"export on earth"->"MathSoft"->"Mathcad"->"Mcad.exe"

Input examples

Example: Definition of a constant

(k=1.38066*10^-23J/K)

Type:

k

:

1.38066

* (Multiplication)

10

^ (exponent)

-23

(going back to the baseline with cursor right)

J

/ (division)

K

You can check the result by entering:

k =

If the result is set to zero, double

Click on the result and set in the Numeric format menu the “Nulltoleranz” to 50

(mark “Als Standard für das Arbeitsblatt”)

Example: definition of a range

Enter the temperature T as a range between 10K and 300K

Type:

T

:

10

*

K

,

20

*

K

;

300

*

K

Example: Definition of a function:

Qvib=∑(exp[hν(i+0.5)/kT]), i=0…100

Type:

i

:

0

,

1

;

100

ν

:

1.144335

*

10^14

*

1/s (unit)

h: 6.626176 * 10 ^-34 * J * s

qvib(T)

:

∑

i (index)

e

^

-h * v * (i+0.5)/k*T

Plot the result:

choose xy diagram from the pull down menu

enter the objects for x and y axis (x-axis: T;

y-axis: qvib(T))

Constants needed for the task:

Avogadro’s constant: NA=6.022045*10²³

Planck’s constant: h=6.626176*10^-34Js

Speed of light: c=2.997935*10⁸m/s

Boltzmann’s constant k=1.380662*10^-23J/K

Rotational constant(HD) B=9.06927*10^-22J

Vibrational constant v=1.144335*10¹⁴1/s