Issues with correct date formatting in where clauses

Hi Folks

I am trying to figure out the most accurate and efficient way to select on a date in a where clause

I have been down this road before and I keep getting mixed up so hoping you can assist

vercdate is defined as a date in my table

define x_date1=20140101
define x_date2=20141231

variable v_date1 varchar2(8)
variable v_date2 varchar2(8)

exec :v_date1  :=&x_date1;
exec :v_date2  :=&x_date2;

i am trying the following clauses with bind and defined variables and not sure which syntax would be most efficient and accurate

Any advise is greatly appreciated