Home page
Back to chemistry page
If you copy and paste the program source code below into a text editor, you can easily compile and run this.
(This class file name is twoele, so save this text editor as "twoele.java", and compile it.)
In this program, we first choose a two-electron atom or ion whose energy we want to calculate, and input the chosen two-electron ion's atomic number Z = 2 (= He = helium ), 3 (= Li+ = singly-ionized lithium ), 4 (= Be2+ = doubly-ionized beryllium ), 5 (= B3+ ), 6 (= C4+ ), 7 (= N5+ ), 8 (= O6+ ), 9 (= F7+ ), 10 (= Ne8+ ), 11 (= Na9+ ), 12 (= Mg10+ ), 13 (= Al11+ ). 14 (= Si12+ ), 15 (= P13+ ), or 16 (= S14+ )...
Next we input the initial x-coordinate r1 (in MM) of electron 1, and the absolute value of the total energy E (in eV) of the two-electron atoms (ions) that we want to calculate.
From the inputted values, this program computes electron's orbits by calculating Coulomb forces and de Broglie wavelength at short time intervals, outputs the y component of electron 1 velocity (= which should be zero in symmetrical orbit around a nucleus ) after the electron moves a quarter of its orbit, and WN (= the number of de Broglie's waves included in one quarter of the orbital ).
Here 1 SS = 1 × 10-23 second and 1 MM = 1 × 10-14 meter.
The initial x-coodinate is automatically increased per calculation until +100.
import java.util.Scanner;
class twoele {
public static void main(String[] args) {
// input Z, r1 and |E|
Scanner stdIn=new Scanner(System.in);
System.out.println("Atomic number Z ? (He=2, Li+=3, Be2+=4, B3+=5, C4+=6, N5+=7...)");
double Z=stdIn.nextDouble();
System.out.println("r1 between nucleus and electron 1 (MM)？ ");
double r=stdIn.nextDouble();
System.out.println("total energy |E| of the two-electron atom (eV) ? ");
double E=stdIn.nextDouble();
double me=9.1093826e-31;
double pai=3.141592653589793; double epsi=8.85418781787346e-12;
double h=6.62606896e-34; double ele=1.60217653e-19; double nucle=2.0*me; double nuclee=0.0;
if (Z == 2 ) { nucle = 6.64465650e-27; nuclee=nucle;} // He alpha particle
if (Z == 3 ) { nucle = 1.1646e-26; nuclee=nucle;} // Li7 nucleus
double rm=(2.0*me*nucle)/(2.0*me+nuclee); rm=rm*0.5; // reduced mass ( He, Li )
double Ene=-((4.0*Z-1)*(4.0*Z-1)*ele*ele*ele*ele*me)/(64.0*epsi*epsi*h*h);
Ene=Ene*6.241509e18; System.out.printf("Wrong Ene:%.3f\n", Ene); // Energy of circular orbit
for (int i=1;i < 100;i++) { // repeat until r1=initial r1+100
// poten = potential energy
double poten=-(2.0*Z*ele*ele)/(4.0*pai*epsi*r)+(ele*ele)/(4.0*pai*epsi*2.0*r);
//vya= total E-potential energy
double vya=-(E*1.60217646e-19)-poten*1.0e14;
if (vya > 0) {
// vyb=electron initial velocity (m/sec)
double vyb=Math.sqrt(vya/me);
double VY=vyb*1.0e-9; // change m/sec to MM/SS
double prexx=r; double VX=0.0; double WN=0.0; double preyy=0.0;
double yy,vk,preVY,preWN,midWN,leng,wav; double xx=0.0;
do {
xx=prexx+VX; yy=preyy+VY; //electron 1 position after 1SS
preVY=VY;preWN=WN ;
vk=VX*VX+VY*VY;
leng=Math.sqrt(vk)*1.0e-14; // moving length (m) for 1 SS
wav=h/(rm*Math.sqrt(vk)*1.0e9); // de Broglie wavelength (m)
WN=WN+leng/wav; // add de Broglie wavelength
//calculation of VX,VY from Coulomb force
double ra=Math.sqrt(prexx*prexx+preyy*preyy); // between nucleus and electron
double rb=Math.sqrt(4.0*prexx*prexx+2.0*preyy*preyy); // between two electrons
// change MM to meter
ra=ra*1.0e-14; rb=rb*1.0e-14;
prexx=prexx*1.0e-14; preyy=preyy*1.0e-14;
double ac=(ele*ele)/(4.0*pai*epsi*rm);
// acceleration (MM/SS^2)
VX=VX+1.0e-32*ac*prexx*(-Z/(ra*ra*ra)+2.0/(rb*rb*rb));
VY=VY+1.0e-32*ac*preyy*(-Z/(ra*ra*ra)+1.0/(rb*rb*rb));
prexx=xx;preyy=yy;
} while (xx >=0); // electron has moved one quater of an orbit?
if (VY > -0.0001 && VY < 0.0001) { // last VY condition
System.out.print("r1: "+r+" ");
System.out.printf("VX:%.6f", VX);
System.out.printf("VY:%.6f", VY);
System.out.printf("preVY:%.6f", preVY);
midWN=(preWN+WN)/2.0; System.out.printf("midWN:%.6f\n", midWN);
}
} r=r+1;
}}}