Mantrashave to be used scientifically. You cannot use one mantra for all the chakras. Each individual chakras has it’s own specific resonance, when we say the mantras in the Sanskrit language, the ‘sound’ made by a person or group of people resonates at a particular frequency which is individual to that particular chakra(s).
Shri Mataji Nirmala Devi explains this concept in 6 extracts from 6 different lectures.