The mantra mentioned in the Purana is
JAPAKUSUMA SANKASHAM KASHYAPEYAM MAHADYUTIM ||
TAMORIM SARVA PAPAGHNAM PRANATOSMI DIWAKARAM ||
Cryptic mantras is as follows:
OM HRAM HRIM HRAUM SAH SURYAY NAMAH' ||
General mantra is as follows :
OM GHRINI SURYAY NAMAH ||
Any of the above given mantras can be chanted repeatedly with devotion.
The mantras should be chanted for 7000 times during the dawn period.