Retrive Data into NotMapped Propery in MVC 4 Entity Framework using Stored Prcedure

Below is my Model class

 public class CPUDetail
    {
        public int CPUDetailId { get; set; }
        [Required]
        [Display(Name = "Quantity")]
        public int Qty { get; set; }
        public DateTime CreatedDate { get; set; }
        public int CreatedBy { get; set; }
        public DateTime ChangedDate { get; set; }
        public int ChangedBy { get; set; }

        [Required]
        [Display(Name = "CPU Master")]
        public int CPUMasterId { get; set; }
        public virtual CPUMaster CPUMaster { get; set; }

        [Required]
        [Display(Name = "SubCategory")]
        public int SubCategoryId { get; set; }
        public virtual SubCategory SubCategory { get; set; }

        [NotMapped]
        public string SubCategoryNme { get; set; }
    }

for retrive data code in controller

 public JsonResult GetDetail(int CPUMasterId)
        {
            string str = "";
            CPUDetail cpu = new CPUDetail();
            try
            {
                _list = CPUDetailRepository.GetCPUDetailByCPUMasterId(CPUMasterId).ToList();
                CPUMasterId = 0;
                str = "Success";
            }
            catch (Exception)
            {
                str = "Success";
            }
            return Json(_list, JsonRequestBehavior.AllowGet);
        }

plz have look in this code...