how to send notification to seller when payment is received
Assuming author of product is also seller, You can do this with a rule using loop and author:mail. Try importing this rule and see how it works

{ "rules_e_mail_seller_checkout_notification" : {
"LABEL" : "E-mail seller checkout notification",
"PLUGIN" : "reaction rule",
"REQUIRES" : [ "rules", "uc_cart" ],
"ON" : [ "uc_checkout_complete" ],
"DO" : [
  { "LOOP" : {
      "USING" : { "list" : [ "order:products" ] },
      "ITEM" : { "list_item" : "Current list item" },
      "DO" : [
        { "mail" : {
            "to" : "[list-item:node:author:mail]\u000D\u000A",
            "subject" : "OrderID: [list-item:order-id] Product: [list-item:title]",
            "message" : "Order: [list-item:order-id]\u000D\u000ANid: [list-item:nid]\u000D\u000ATitle: [list-item:title]\u000D\u000AQty: [list-item:qty]\u000D\u000APrice: [list-item:cost]\u000D\u000ASeller: [list-item:node:author]",
            "language" : [ "" ]
          }
        }
      ]
    }
  }
]


}
}

source - https://www.drupal.org/node/1830962