The phrase "absent smile" is correct and usable in written English.
It can be used to describe a smile that is missing or not present, often conveying a sense of sadness or lack of joy.
Example: "Her eyes sparkled with joy, but her lips wore an absent smile, hinting at her hidden sorrow."
Alternatives: "missing smile" or "lack of smile".
— The Jets trudged deceptively into the visitors' locker room at Ralph Wilson Stadium, absent smiles, fist pumps, or any of the usual signs of celebration.
"I don't think Manny is very far from that". Ramirez is not far from Bonds in many respects, exciting yet aggravating, present yet absent, smiling while sneering.
He entered his news conference Monday night drenched in sweat, absent a smile or any outward signs of celebration, yet with his fourth and most unlikely national title already secured.
She sat there with that chewed-in yet absent-minded smile on her face, as if she'd been given a present that she knew she'd like, even though she hadn't got the wrapping off it yet.
Afterward, Turkoglu walked through the locker room in his robe with customary flair but with his normally accompanying smile absent.
Wanda picks up a man in a bar, but their talk is absent — she just smiles and chats, and their voices go unrecorded.
For once, that flashing smile is absent.
But his incisiveness, his sneaky smile, were absent.
Later she sits and watches the clock, waiting, and smiling a secret smile, amused, absent and speculative.
This smile, mostly absent from Janacek's two later operas, "The Makropulos Case" and the harrowing "From the House of the Dead," hovers over "The Cunning Little Vixen".
In many particulars — her South African upbringing, her uprooted life, her acute postpartum depression after the birth of her last child, her hard-working and often absent husband, her radiant smile overlying pain and her powerlessness before her own self-destructive urges — Carol resembled my mother.
