Tkinter Login app

import tkinter as tk
root = tk.Tk()
root.geometry('400x200+500+200')
root.configure(bg="powder blue")




def open_login_screen():
    loginWin = tk.Tk()
    loginWin.geometry("300x140+560+240")
    logusernameLabel = tk.Label(master=loginWin,text="Username: ")
    logusernameLabel.grid(row=0,column=0,padx=20)
    logusernameField = tk.Entry(master=loginWin,width=30)
    logusernameField.grid(column=1,row=0,pady=10)

    #password label

    logpasswordLabel = tk.Label(master=loginWin,text="Password: ")
    logpasswordLabel.grid(row=1,column=0,padx=20)
    logpasswordField = tk.Entry(master=loginWin,width=30)
    logpasswordField.grid(column=1,row=1,pady=10)
    logsubmitLogin = tk.Button(master=loginWin,text="Login",width=16)
    logsubmitLogin.grid(row=2,column=1)
    logbackButton = tk.Button(master=loginWin,text="Back",width=8,command=open_main_screen)
    logbackButton.grid(row=2,column=0)


def open_register_screen():
    registerWin = tk.Tk()
    registerWin.geometry("400x200+560+240")
    regusernameLabel = tk.Label(master=registerWin,text="Username: ")
    regusernameLabel.grid(row=0,column=0,padx=20)
    regusernameField = tk.Entry(master=registerWin,width=30)
    regusernameField.grid(column=1,row=0,pady=10)

    regemailLabel = tk.Label(master=registerWin,text="Email: ")
    regemailLabel.grid(row=1,column=0,padx=20)
    regemailField = tk.Entry(master=registerWin,width=30)
    regemailField.grid(column=1,row=1,pady=10)

    #password label

    regpasswordLabel = tk.Label(master=registerWin,text="Password: ")
    regpasswordLabel.grid(row=2,column=0,padx=20)
    regpasswordField = tk.Entry(master=registerWin,width=30)
    regpasswordField.grid(column=1,row=2,pady=10)

    regconfirmPasswordLabel = tk.Label(master=registerWin,text="Confirm Password: ")
    regconfirmPasswordLabel.grid(row=3,column=0,padx=20)
    regconfirmPasswordField = tk.Entry(master=registerWin,width=30)
    regconfirmPasswordField.grid(column=1,row=3,pady=10)
    #registerUser(username,email,password,confirmPassword)


    def  register(confirmPassword=regconfirmPasswordField.get(),password=regpasswordField.get()
									,email=regemailField.get(),username=regusernameField.get()):
        print(confirmPassword,password)
        infoFile = open('{0}_account_info.txt'.format(username),'w+')
        infoFile.write('Username: {0}\nEmail: {1}\nPassword: {2}\n Thank you for creating yourSami(tm) 									Account!'.format(username,email,password))
        infoFile.close()
        logFile = open('{0}accinf__do_not_edit_.txt'.format(username),'w+')
        logFile.write('{0};{1};{2}'.format(username,email,password))
        logFile.close()


    regsubmitRegister = tk.Button(master=registerWin,text="Register",width=16,command=register)
    regsubmitRegister.grid(row=4,column=1)



def open_main_screen():
    global loginButton
    global registerButton
    try:
        usernameField.destroy()
        passwordField.destroy()
        submitLogin.destroy()
        usernameLabel.destroy()
        passwordLabel.destroy()
        backButton.destroy()
        loginButton = tk.Button(master=root,text="Open Login Screen",command=open_login_screen)
        loginButton.grid(pady=40,padx=40,row=0,column=1)
        registerButton = tk.Button(master=root,text="Open Register Screen",command=open_register_screen)
        registerButton.grid(row=0,padx=40,pady=40,sticky='N',column=0)
    except:
        loginButton = tk.Button(master=root,text="Open Login Screen",command=open_login_screen)
        loginButton.grid(pady=40,padx=40,row=0,column=1)
        registerButton = tk.Button(master=root,text="Open Register Screen",command=open_register_screen)
        registerButton.grid(row=0,padx=40,pady=40,sticky='N',column=0)

open_main_screen()
root.mainloop()