SharePoint User Token Code

try

            {

                SPSite tempSite = new SPSite(siteURL);

                string loginNameInFull = @"i:0#.w|" + username;

                SPUserToken userToken = tempSite.OpenWeb().AllUsers[loginNameInFull].UserToken;

                using (SPSite site = new SPSite(siteURL, userToken))

                {

                    using (SPWeb web = site.OpenWeb())

                    {

                        SPList olist = web.Lists[listName];

                        SPListItemCollection ocol = olist.Items;

                        return ocol;

                    }

                }

            }

This is passing credentials to Windows Authentication

UserName append with "i:0#w|"