Explicit conversion of column in Table Partition in SQL Server - sql-server

Question

I have table like below:
CREATE TABLE [dbo].[PartitionExample]
(
[dateTimeColumn1] [datetime] NOT NULL,
CONSTRAINT [PK_PartitionExample] PRIMARY KEY CLUSTERED
(
[dateTimeColumn1] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY =
OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
I have created Partition Function like below:
CREATE PARTITION FUNCTION DateRangePF (INT)
AS RANGE RIGHT FOR VALUES ( 20180601,20180901,20181201,20190301)
Then, I have created Partition Scheme for it:
CREATE PARTITION SCHEME DateRangePS
AS PARTITION DateRangePF TO
(FG032018_SampleDB,FG062018_SampleDB,FG092018_SampleDB,
FG122018_SampleDB,FG032019_SampleDB);
Now, When I am applying the partition scheme to this table, I want to apply explicit conversion of [dateTimeColumn1] column of datetime data type to INT Data Type. But when I tried it, I got syntax error:
ALTER TABLE [dbo].[PartitionExample] ADD
CONSTRAINT [PK_PartitionExample] PRIMARY KEY CLUSTERED
(
dateTimeColumn1 ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, ALLOW_ROW_LOCKS =
ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 90)
ON DateRangePS(
convert(INT, CONVERT(CHAR(8), dateTimeColumn1, 112));
Can you guys please let me know
how explicit conversion can be implemented in such scenarios.
Also would it perform better when I will perform explicit conversion of datetime column or char(8) column to INT Column for partition.
Thank you for your help.